Magnetic and electronic properties of alpha-NaMnO2

The magnetic and electronic properties of alpha-NaMnO2 are investigated by performing the first-principles density functional calculations. A semiconducting ground state with high spin Mn is found. The magnetic coupling within a Mn layer is antiferromagnetic and frustrated, while the coupling between layers is very weak. Spatially anisotropic exchange is found within a Mn layer. The large Jahn-Teller distortion lowers the energy of d(3r2-z2) orbital, leading to the stabilization of high spin Mn and ferromagnetic orbital ordering. Moreover, GGA+U studies show that alpha-NaMnO2 has the mixed characteristics of Mott-Hubbard insulators and charge transfer insulators. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3074783]