Effect of post-annealing on microstructural and magnetic properties of CoFe2O4:MgO nanocomposite films on MgAl2O4(001) substrates

Heteroepitaxial CoFe2O4:MgO nanocomposite films were grown on single-crystalline MgAl2O4(001) substrates by the pulsed laser deposition technique. The effect of post-annealing on microstructural and magnetic properties of the nanocomposite films has been systematically investigated. In the heterosystems, misfit dislocations bounding anti-phase domain boundaries release the epitaxial strain between the nanocomposite films and the substrates. Compared with the as-grown films, the Co distribution and the epitaxial strain state change in the post-annealed nanocomposite films. Additionally, the in-plane saturation magnetization (M-s) and coercivity (H-c) decrease, while M-s decreases but H-c increases along the out-of-plane direction of the post-annealed nanocomposite films. Our findings indicate that a feasible strategy to change the physical properties of the single-phase film by post-annealing can be applied to the nanocomposite films containing spinel ferrites.