Local Structure of Amorphous EuO–TiO 2 Thin Films Probed by X ‐Ray Absorption Fine Structure

We have investigated the local structure of amorphous oxides in EuO–TiO 2 system to understand the mechanism that gives rise to curious ferromagnetic properties recently observed in the system. X ‐ray absorption spectroscopy has been performed on amorphous EuTiO 3 and Eu 2 TiO 4 thin films prepared by the pulsed‐laser‐deposition method. The Ti K ‐edge X ‐ray absorption near‐edge structure ( XANES ) and extended X ‐ray absorption fine structure ( EXAFS ) data analyses reveal that the coordination number of Ti 4+ in the amorphous thin films is around 4, which is in sharp contrast to their crystalline counterparts, where Ti 4+ ions are octahedrally coordinated by oxide ions. It is therefore inferred that Ti 4+ acts as a network‐forming cation in the random network structure of the amorphous oxides. From the Eu L 3 ‐edge EXAFS data analyses, it is found that the coordination number of Eu 2+ is much lower and the nearest Eu–O bond length is shorter in the amorphous thin films than in the crystalline counterparts. The amorphization‐induced enhancement of ferromagnetic interactions observed in the EuO–TiO 2 system is discussed in terms of the local environment around Eu 2+ ions.