Electronic structure and magnetic properties of Co doped TiO2 thin films using X-ray absorption spectroscopy

The thin film of Ti0.95Co0.05O2−δ has been grown on LaAlO3 (100) substrate using pulsed laser deposition method. X-ray diffraction, near-edge X-ray absorption fine structure (NEXAFS) spectroscopy, X-ray magnetic circular dichroism (XMCD) and magnetic hysteresis loop measurements were used to fully understand the origin of ferromagnetism. Our structural analysis reveals a single phase nature of the film and excludes the presence of any secondary phase. NEXAFS spectra collected at Ti L3,2, and Co L3,2 -edge infer that Co and Ti ions are in 2+ and 4+ valence states, respectively. Multiplet calculation performed at Co L3,2 -edge also support the experimental observations and shows that Co ions are in 2+ valence state in Oh (octahedral) symmetry. Zero field cooled and field cooled magnetization infer that TC of Ti0.95Co0.05O2−δ film is above room temperature. DC magnetization hysteresis loop study and XMCD measurement at Co L3,2 -edge reflect that Ti0.95Co0.05O2−δ film exhibits ferromagnetic ordering at room temperature.