X-ray absorption near-edge structure spectroscopy and first-principles calculations

were combined in order to study the local and electronic structures of rutile

Co:TiO2 thin films exhibiting room-temperature ferromagnetism. It was revealed

that CoTi

2+, substituted at Ti sites, formed a CoTi

2+-VO complex, with the O vacancy

being generated in the annealing process. The O vacancy introduced a spin-split

donor impurity band with a t2g character within the gap region. It was proposed that

the strong exchange interaction between the localized carriers captured by the O

vacancy and the substitutional Co ions led to the ferromagnetism of the Co:TiO2

thin films.

Oxygen Vacancy Effect on Room-Temperature Ferromagnetism of Rutile Co:TiO2

Thin Films. W.Yan, Z.Sun, Z.Pan, Q.Liu, T.Yao, Z.Wu, C.Song, F.Zeng, Y.Xie,

T.Hu, S.Wei: Applied Physics Letters, 2009, 94[4], 042508