A simulation study on the electromagnetic structure and optical properties of Co doped TiO2

Abstract

Rutile TiO2 with intrinsic defects or doped by specific elements will emerge excellent electromagnetic property and optical characteristics, such as room temperature ferromagnetism. In this study, we studied the effects of intrinsic defects and Co atoms on the electromagnetic structures and optical properties of rutile TiO2 by Density Functional Theory. The results show that the magnetic moment is produced by intrinsic defects such as VO and Tii while the Co atom can also polarize the system. The magnetism of Co doped TiO2 does not come entirely from Co atom. There will be a change in charge population when O and Ti are close to Co atoms, which will produce local spin magnetic moment. The hybridization of Co:3d, Ti:3d and O:2p orbitals leads to the generation of new impurity levels in the band gap, which reduces the Eg of rutile TiO2 and improves the visible light absorption, resulting in the red-shift of the light absorption edge of Co doped TiO2. In addition, the optical properties of both pure rutile TiO2 and Co doped TiO2 are anisotropic, especially along [001] direction.