Band calculations of interstitially modified iron and rare-earth iron compounds

The electronic structures of RFe12X(1-12 system), R2Fe17X3(2-17), and R2Fe14X(2-14) hard magnetic materials were reviewed systematically for R = Y or Gd and X = N, C or B. They were calculated by the LMTO-ASA or FLAPW method within the framework of the local-spin-density (LSD) approximation. In the 1-12 or 2-17 system, the magnetic moments of Fe are reduced around C or B, but not around N. The microscopic mechanism will be discussed in connection with the resonance peak just above the Fe-3d bands in the majority-spin slate. It is also shown that the strong uniaxial magnetic anisotropy is realized through the crystal field at R site due to the hybridization between X-2p and R-5d states. The calculated results of Fe-X system are discussed only briefly.