Magnetic and structural properties of cobalt ferrite thin films and structures

Abstract

Co-ferrite (CoFe2O4) films and patterned arrays were prepared using ion-beam sputtering at elevated substrate temperatures on two types of substrate; MgO (001) and SrTiO3(001). The influence of structure, epitaxy, and interface chemistry on the magnetic properties is analyzed as a function of deposition temperature and annealing. Whereas epitaxial growth and high crystallinity of the CoFe2O4 films is obtained for optimized deposition conditions on both types of substrates, magnetic properties are significantly depleted in films on MgO due to interfacial diffusion of Mg. Although lattice mismatch is much higher, a saturation magnetization of μ0MS = 420 mT not far below bulk values and a remanent magnetization of 142 mT is obtained in 30 nm thin films on SrTiO3. Patterned arrays of CoFe2O4 show an in-plane easy magnetization axis in contrast to homogeneous films before patterning.