(111)-Oriented Co0.8Fe2.2O4+δ thin film grown by pulsed laser deposition: structural and magnetic properties

The perfect (111)-oriented Co0.8Fe2.2O4+δ thin films were grown on Pt(111)/Si substrate by pulsed laser deposition technique. Co0.8Fe2.2O4+δ film grown at oxygen pressure of 10 mTorr (optimum condition) has the highest (111)-orientation degree, the lowest surface roughness, uniformly compacted nanosize grain-feature structure (50–80 nm), and the highest magnetization. The Fe K-edge X-ray absorption near edge structure analyses revealed that, in Fe-doped CoFe2O4 film, the Fe also exists as Fe3+ (Co0.8Fe2.2O4+δ), which affects the lattice parameter as well as magnetic properties. The magnetic properties (saturation magnetization, coercivity, and squareness) of Co0.8Fe2.2O4+δ thin film are significantly higher than those of CoFe2O4 film. Moreover, the (111)-oriented Co0.8Fe2.2O4+δ thin film demonstrates strong in-plane magnetic anisotropy, which results from orientation, as well as the stress-induced magnetic anisotropy.