Stability and magnetism of FeN high-pressure phases

Most of the experimentally discovered compounds in the iron–nitrogen system belong to the low concentration part of the Fe–N phase diagram. In our paper, which is based on ab initio calculations, we have studied the formation and stability of high-pressure iron mono-nitride phases, and in particular a new magnetic phase with a NiAs-type structure. We have investigated the role of dynamic, thermodynamic and electronic properties, such as electronic correlations and pressure-induced phase stabilisation. Additionally, we have demonstrated that the new hexagonal FeN phase is stable over a wide range of external pressures and can persist at zero pressure as a metastable phase. Further, we have shown that this phase has a relatively low Curie temperature and may possess non-collinear magnetism.