Determination of Co spin state in rutile Co:TiO2
ABSTRACT X-ray absorption near-edge structure (XANES) and first-principles calculations are employed to determine the Co spin state in the Co-doped TiO 2 thin films. Based on the experiments and the theoretical calculations, we find that the transition of Co 1s electron to the unoccupied Co 3d eg states is clarified from the pre-edge single-peak in the Co K -edge XANES spectrum of the Co-doped TiO 2 thin film, and that the Co 3d t2g states are occupied while the eg states are partially unoccupied. This suggests a low-spin configuration of the substitutional Co 2+ in the Co-doped TiO 2 thin film. The studies demonstrate the ability of Co K -edge XANES to provide information on spin state of Co ions in the Co-doped TiO 2 .