Relations of electronic energies and magnetic moments of tetra-3d metal (Mn, Fe, Co and Ni) nitrides calculated using a plane-wave basis method

Abstract

Geometrical optimization of tetra-3d metal nitrides (Mn 4N, Fe 4N, Co 4N, and Ni 4N) has been performed and the relations of their energies ( E) and their total magnetic moments ( M) are obtained by plane-wave-basis density-functional calculations without any assumption of specific spin arrangement. The E vs. M relations obtained for Fe 4N and Mn 4N have a bimodal character. The ground state of Fe 4N is a high-spin state, which would correspond to the ferromagnetic character, while that of Mn 4N is a low-spin state, which would correspond to the observed ferrimagnetic character. Lattice constants and total magnetic moments of these tetra-3d metal nitrides are almost accurately predicted. From the spin-polarized densities of states curves, Co 4N would have the largest spin polarization ratio of 0.88, which suggests Co 4N can be a candidate material for ferromagnetic electrodes for spin-injection.