Electronic structure and magnetic properties of a new class of hard magnets: R2Fe17Nx(abstract)

Recently discovered R2 Fe17Nx (R=rare earth, x∼3) compounds look promising as permanent‐magnet materials. The addition of N to R2Fe17 compounds almost doubles their Curie temperatures.¹ It also give rise to uniaxial anisotropy in the Sm compound. We have performed spin‐polarized self‐consistent electronic structure calculations in order to understand the magnetic properties. Neutron diffraction and photoemission measurements are used to obtain information on nitrogen site occupancies and electronic structure. For Y2Fe17N3, the calculated site‐dependent Fe moments vary significantly from those for Y2Fe17 (up to ∼1.7 μB), and the total moment per cell agrees very well with experiment. The expansion of the lattice due to nitrogenation lowers the overlap among the Fe atoms in the ion‐only planes thereby increasing their magnetic moments. This leads to an increase in their interatomic exchange interactions and hence the Curie temperature. The Fe atoms in the vicinity of the N atoms overlap strongly with the latter and thus their moments decrease.²