Effects of oxygen vacancy on the electrical and magnetic properties of anatase Fe0.05Ti0.95O2−δ films

• Epitaxial anatase Fe0.05Ti0.95O2−δ thin films were grown on LaAlO3 substrates by pulsed laser deposition under different oxygen atmosphere.
• The influence of oxygen vacancy on the magnetic, optical, and transport properties of Fe:TiO2 ferromagnetic semiconductor films has been investigated systematically.
• The origin of the ferromagnetism was interpreted by a modified bounded magnetic polaron model.

Epitaxial anatase Fe0.05Ti0.95O2−δ (δ: oxygen vacancy) thin films were grown on LaAlO3 substrates by pulsed laser deposition. Structural characterizations by X-ray diffraction confirmed the incorporation of substituting Fe atoms into anatase TiO2 lattice, no impurity phases or clusters formation were detected. The influence of growth oxygen pressure on the crystal structure and properties of Fe0.05Ti0.95O2−δ semiconductor films has been investigated systematically. As the oxygen pressure decreases, more oxygen vacancies are generated in the thin film. At the same time, the optical band gap narrows down and the electrical properties improve correspondingly. Room temperature ferromagnetism was observed in all samples and saturation magnetization increased from 0.8 emu/cm3 to 8.3 emu/cm3 with the increase of oxygen vacancy concentration. Strong correlation between ferromagnetism and oxygen vacancy density was established. This is explained by a modified bounded magnetic polaron model.