We perform the ab initio calculations of the absorption and optical magnetic circular dichroism (MCD) spectra for the Co-doped anatase and rutile TiO2 systems. The obtained MCD spectra correlate well with the absorption spectra, and both are in agreement with the experimental measurements, indicating that the substitutional supercell model is proper for simulating such doping systems. The positive MCD signals around the absorption edge and critical points means the p - d exchange interaction between the O 2p and Co 3d electrons should be ferromagnetic. The results show that the MCD signals do come from the energy band structure, supporting the intrinsic ferromagnetism in the Co-doped TiO2 systems.
|Physical Review B - Condensed Matter and Materials Physics
|Published - 2006