The stability, magnetism and electronic structure of Fe15TMN2 and Fe14TM2N2 (TM=Cr, Mn, Co, and Ni)

The stability, magnetism and electronic structure of Fe15TMN2 and Fe14TM2N2 (TM=Cr, Mn, Co, and Ni) have been investigated using first-principle electronic structure calculations. The results confirmed that Fe16N2 is a thermally metastable phase with a tiny positive cohesive energy. However, we found that the few percentage of 3d TM doping could stabilize Fe16N2. It indicates that Cr and Mn prefer to occupy 8h and 4e sites of Fe16N2, respectively, and both of them have straightly bonded to interstitial N. While Co and Ni prefer to occupy the 4d sites, which do not have nearest neighbour N atoms. It is most significant that the total magnetic moments lose little with increasing doping concentration of Mn and Co, up to 12.5%. If these stablest phases are realized in bulk formation, it would be promising for the research of high performance magnetic iron nitride.