Electronic and magnetic structure of iron nitride, Fe16N2 (invited)

The result of spin-polarized band calculation for Fe16N2 is presented. The most distant Fe atoms from N is found to have the largest magnetic moment. The major role of the N atom is to expand the Fe lattice, leading to the enhancement of the magnetic moments. Quantitatively speaking, the calculated moment of Fe16N2 is about 2.4 μB which is much smaller than the measured value reported. It is also shown that the correction with the orbital magnetic moment and the generalized gradient approximation (GGA) cannot account for this discrepancy. From the point of view of the many body effects, a possibility of the giant moment is also discussed. An important feature of this model is a generation of hopping sites with the N atoms, which likely promotes a ferromagnetic coupling of Fe atoms keeping their large spin-polarization in the atomic limit.