Neodymium magnet

Neodymium magnets is the most widely used commercially rare earth magnets, meaning a strong magnet forged from a rare earth material. Neodymium magnets are alloys of neodymium,iron, and boron to form a tetragonal crystalline structure.it was developed in 1984 by car companies to use commercially. 
A nickel plated neodymium magnet from a bracket from a hard drive 
neodymium magnet balls in a shape of a d20 
The tetragonal crystalline structure neodymium magnets make.
Neodymium magnets have replaced other types of magnets in many applications in modern products that require strong permanent magnets, such as electric motors in cordless tools, hard disk drives and magnetic fasteners.