Electronic band structure and magnetism of Fe16N2 calculated by the FLAPW method

Electronic band structure calculations based on the full-potential linear augmented plane-wave method have been performed for Fe16N2. The calculations are performed with the crystal parameters recently refined [H. Tanaka et al., Acta Mater. 45, 1401 (1997)] in addition to the previous reported structure [K. H. Jack, Proc. R. Sec. London, Ser. A 208, 200 (1951)]. Jack's model (J model) led to the model of Tanaka er al. (T model), where Fe atoms at the 8h site shift to N atoms along the [110] direction. The calculated average moment per Fe atom for the T model is slightly smaller than that for the J model. We cannot theoretically expect a large magnetic moment based on any Fe16N2 structure. The presence of another material that has a large magnetic moment must be considered to explain the large magnetic moment of the Fe-N system.