Local coordination influence on the magnetic properties of iron nitride

The electronic structure and magnetic properties of cubic iron nitrides FeN with NaCl- and ZnS-type structures have been calculated by employing a fir st-principle full-potential linearized muffin-tin orbital method. The resul ts show that the local FeN octahedral coordination with a centred nitrogen atom is an advantageous one with which to exhibit a large exchange splittin g. Meanwhile, the local Fe-N tetrahedral coordination produces a non-magnet ic phase, the ZnS-type structure. A super-exchange interaction can reasonab ly explain the magnetism of the FeN nitrides. In comparison with other Fe-N compounds, we find a linear dependence of the magnetic moment of iron atom s with the volume, which corresponds to the octahedral coordination. Furthe rmore, a magnetic moment instability is presented in the NaCl-type structur e.