Ferromagnetism in laser deposited anatase Ti1-xCoxO2-δ films -: art. no. 115211

Pulsed laser deposited films of Co-doped anatase TiO2 are examined for Co substitutionality, ferromagnetism, transport, magnetotransport, and optical properties. Our results show limited solubility (up to similar to2%) of Co in the as-grown films and formation of Co clusters thereafter. For the Ti0.93Co0.07O2-delta sample, which exhibits a Curie temperature (T-C) over 1180 K, we find the presence of 20-50 nm Co clusters as well as a small concentration of Co incorporated into the remaining matrix. After being subjected to the high-temperature anneal during the first magnetization measurement, the very same sample shows a T(C)similar to650 K and almost full matrix incorporation of Co. This T-C is close to that of as-grown Ti0.99Co0.01O2-delta sample (similar to700 K). The transport, magnetotransport, and optical studies also reveal interesting effects of the matrix incorporation of Co. These results are indicative of an intrinsic Ti1-xCoxO2-delta diluted magnetic semiconductor with T-C of about 650-700 K.