Oxygen vacancy control of electrical, optical, and magnetic properties of Fe_0.05Ti_0.95O₂ epitaxial films

High-quality Fe-doped TiO₂ films are epitaxially grown on MgF₂ substrates by pulsed laser deposition. The x-ray diffraction and Raman spectra prove that they are of pure rutile phase. High-resolution transmission electron microscopy (TEM) further demonstrates that the epitaxial relationship between rutile-phased TiO₂ and MgF₂ substrates is 110 TiO₂₂. The room temperature ferromagnetism is detected by alternative gradient magnetometer. By increasing the ambient oxygen pressure, magnetization shows that it decreases monotonically while absorption edge shows a red shift. The transport property measurement demonstrates a strong correlation between magnetization and carrier concentration. The influence of ambient oxygen pressure on magnetization can be well explained by a modified bound magnetization polarization model.