Electronic and mechanical properties of MgN compound: Prediction of stable half-metallic ferromagnet in NaCl and ZB phases

Abstract

First-principles method within the generalized gradient approximation (GGA-PBEsol) and the modified Becke-Johnson approach (mBJ-GGA-PBEsol) for the exchange-correlation energy and potential were used to investigate the structural, elastic, mechanical and thermal properties of MgN compound in different phases. Various phases of MgN compound were considered, which are NaCl, CsCl, ZB, WZ, NiAs, PtH4I, and Pnma phases. We found that the NaCl phase is the lowest energy phase as a function of the volume. The ferromagnetic phase is energetically favored with respect to the non-magnetic phases, except for the CsCl and PtH4I phases. The calculated elastic properties for the NaCl, ZB and WB phases showed that they are elastically stable. Considering the phonon dynamics of MgN in the NaCl, ZB and WB phases, we observed that the MgN compound in the NaCl and ZB phases is dynamically stable. From electronic band structure and density of states, MgN compound shows half-metallic behavior in NaCl and ZB phases. The NaCl phase was found to have a robust half-metallic character with respect to the lattice compression and expansion. The half-metallic and magnetic character found in MgN compound is attributed to the presence of spin polarized 2p orbitals of the nitrogen atom. We found that the MgN compound in the NaCl and ZB phases is a half-metallic ferromagnet with magnetic moment of 1 μB per formula unit and half-metallic gaps of 0.01 eV (1.34 eV) and 0.57 eV (1.85 eV) within the GGA-PBEsol (mBJ-GGA-PBEsol) for the NaCl and ZB phases respectively.