Cation and magnetic orders in MnFe2O4 from density functional calculations

Abstract

MnFe2O4 generally crystallizes in a mixed phase consisting of both the normal and inverse spinel structures with the fitted experimentally determined saturation moments of 5 and 3 μB per formula, respectively. Employing the density-functional methods with the generalized gradient approximation for the exchange-correlation energy functional and the on-site Coulomb effect (GGA+U), we have studied this material through exploring various cation distributions and magnetic orders of the system. We demonstrate that the magnetic moment can be accounted for by the high-spin Mn2+ cations at the tetrahedral site in the normal spinel structure and by the intermediate-spin Mn2+ cations at the octahedral site in the inverse spinel structure. That is, the results support the single-valence state for this material. The corresponding energetics, exchange interactions, and electronic properties are also presented and discussed.