Ferromagnetic properties of anatase Ti1−xFexO2−δ thin films

Abstract

The effects of Fe doping on the magnetic and electronic properties of reduced TiO2−δ thin films have been investigated. Anatase Ti1−xFexO2−δ films exhibit a ferromagnetic behavior at room temperature for a certain range of Fe doping. Conversion electron Mössbauer spectroscopy measurements indicate that Fe2+ and Fe3+ ions coexist in the Fe-doped films, substituting the octahedral Ti4+ sites. The contribution of possible Fe3O4 clusters to the observed ferromagnetism is not likely to happen. The Ti1−xFexO2−δ films exhibit a p-type character by Hall effect measurements but the observed ferromagnetism turns out to be independent of the hole concentration. The observed ferromagnetism in the Ti1−xFexO2−δ films can be explained in terms of a direct ferromagnetic coupling between two neighboring Fe3+ ions via an electron trapped in oxygen vacancy nearby.