Surface d0 half-metallicity of rocksalt MgN from first-principles

Abstract

Using the first-principles full-potential linearized augmented plane-wave method, we extend the recent study on above-room-temperature d0 half-metallic ferromagnetism in bulk rocksalt MgN (A. Droghetti, N. Baadgi, S. Sanvito, Phys. Rev. B 80 (2009) 235310) to the (111) and (001) surfaces. It is shown that both the (001) surface and the N-terminated (111) surface are still half-metallic, but the Mg-terminated (111) surface loses the half-metallicity. The N atomic magnetic moment at the (001) surface has small difference compared to that in the bulk MgN due to the keep of Mg–N bond at the surface, but the difference is very large for the case of the (111) surface due to the complete break of Mg–N bond at the surface. In addition, we reveal form the calculated surface free energy that the Mg-terminated (111) surface and the (001) surface are more favorable than the N-terminated (111) surface when rocksalt MgN thin films are fabricated.