Structural, magnetic, and electrical properties of spin coated ilmenite-pseudobrookite xFeTiO_3-(1-x)Fe_2O_3 thin films

摘要

We report on the structural, magnetic, optical, and electrical properties of iron titanate thin films prepared using a spin-coating technique having nominal compositions of FeTiO_3 and Fe_(1.4)Ti_(0.6)O_3. X-ray diffraction measurements show clear evidence for the presence of both ilmenite and pseudobrookite crystal structures, which is confirmed using Raman spectroscopy. X-ray photoemission spectroscopy studies indicate that Fe is present mainly in the 2+ valence state, with some Fe~(3+) present on the more heavily oxidized surface of the films. The as-prepared samples exhibit weak ferromagnetism at room temperature. While the valence state of Fe is not significantly affected by vacuum annealing, the saturation magnetization is increased dramatically, reaching nearly 220 emu mole~(-1) for the Fe-rich film. The optical band gap was found to be roughly 2.0 eV for all samples, with negligible changes on vacuum annealing.