First-Principles Study of the Role of Cu in Improving the Coercivity of Nd-Fe-B Permanent Magnets

The strongest permanent magnets are made of Nd-Fe-B alloys, but at high temperatures their coercivity drops. The interfaces of subphases with the bulk seem to be important, and here a little bit of copper helps, but why? The authors' calculations reveal that Cu naturally replaces the interfacial Fe that suppresses the magnetic anisotropy of nearby Nb, thus improving the alloy's coercivity. This physical insight will help to guide the engineering of improved magnets for $e.g.$ motors in cars and wind turbines.