Room-temperature ferromagnetism and optical properties in Mg-doped TiO2: A density functional theory investigation

Abstract

The magnetic and optical properties of Mg-doped anatase TiO2 have been theoretically investigated using the LDA+U method. The total induced moments are about 2 μB, which mainly localize on the nearest apical oxygen atoms. Moreover, the hole-induced interactions indicate that the magnetic moments prefer to the ferromagnetic coupling with the antiferromagnetic state lying 1160 meV higher in energy. This implies that the ferromagnetic state can be stable against thermal fluctuations up to room temperature. Additionally, the Mg doping is able to enhance the absorption efficiency of solar spectrum, especially in the near-infrared light region, which origins from the isolated O 2p states above the valence-band maximum rather than the effect of band-gap narrowing.