X-ray absorption and magnetic circular dichroism characterization of Fe-doped TiO2−δTiO2−δ thin films

We report x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) measurements of both paramagnetic and ferromagnetic Ti1−xFexO2−δTi1−xFexO2−δ thin films. Fe L3,2L3,2 edge XAS spectra showed that the Fe ions in our samples were in mixed valence states and that the Fe2+/Fe3+ ratio decreased with increasing oxygen partial pressure. Finite XMCD signals were observed only for the Fe2+ state in the ferromagnetic sample. These findings indicate that the observed ferromagnetism in Ti1−xFexO2−δTi1−xFexO2−δ originates from ferromagnetic interactions between Fe2+ local spins.

► The Fe ions in Ti1−xFexO2Ti1−xFexO2 films are mixed valence states of Fe2+ and Fe3+.
► The valence state of Fe in Ti1−xFexO2Ti1−xFexO2 films systematically changes with PO2 during deposition.
► X-ray magnetic circular dichroism signals were observed only in ferromagnetic Ti1−xFexO2Ti1−xFexO2 film.
► The ferromagnetic interaction between Fe2+ local spins plays an essential role in Ti1−xFexO2Ti1−xFexO2.