SELF-CONSISTENT CALCULATIONS FOR THE ELECTRONIC-STRUCTURES OF IRON NITRIDES, FE3N, FE4N AND FE16N2

The spin-polarized band calculations for the iron nitrides, Fe3N, Fe4N and Fe16N2, have been performed with use of the LMTO-ASA method in the frame of local spin density functional formalism. The results show that the most distant Fe atoms from N have the largest magnetic moment. This can be ascribed mainly to the transfer of the down spin electrons, which is caused by the electronic interference due to the interstitial N atoms. The central role of the N atom is to bring about the large magnetic moments through the lattice expansion. Concurrently, the N atoms promote an itineracy of electrons and then in turn prevent the exchange-splitting. This leads to the behavior that the lower N concentration gives the larger magnetic moments. Quantitatively, the results are in fair agreement with the experimental results except for Fe16N2 whose measured value is considerably larger than the calculated result.