First-Principles Prediction of Possible Rare-Earth Free Permanent Magnet of Tetragonal FeCo with Enhanced Magnetic Anisotropy and Energy Product through Interstitial Nitrogen

Abstract

Permanent-magnet applications such as electric motors demand a high energy product (simultaneously high saturation magnetization and uniaxial magnetic anisotropy) and Curie temperature, preferably in $3d$ metals without any rare-earth elements. The authors' first-principles calculations highlight a promising pathway to achieving these properties in $B2$-ordered FeCo alloy, by interstitial doping with $2p$-electron nonmetal elements, such as N. This prediction could have real impact on the manufacturing of practical, rare-earth-free, high-performance permanent magnets.