Ab Initio Study of the Relation between the Structural, Magnetic, and Optical Properties of Normal and Inverse MnGa2O4 Spinels

—The electronic, magnetic, and optical properties of MnGa2O4 in the structure of the normal and inverse spinels are subjected to an ab initio investigation and comparison. The generalized gradient approximation (GGA) predicts that the normal MnGa2O4 spinel is a semiconductor with a bandgap of about 0.7 eV, and a bandgap in the structure of the inverse spinel appears only in terms of the GGA + U approach. A simple exchange interaction model is used to calculate exchange integrals. In both structure types, MnGa2O4 exhibits antiferromagnetic behavior, and the normal structure is energetically favorable. The inverse spinel becomes energetically favorable only when a negative pressure is applied. The absorption spectra of the normal spinel are found to have a spectral window at a wavelength larger than 450 nm.