Epitaxial cobalt ferrite thin films provide a model system for understanding the magnetic properties of spinel structure ferrite thin films. We demonstrate that the anomalous magnetic behavior, observed in our antiphase-boundary-free films, can be explained in terms of cation distribution and lattice distortions. The magnetic anisotropy is a delicate balance between strain anisotropy, due to internal lattice strain or equivalent external strain effects, and magnetocrystalline anisotropy, due to cation distribution. By annealing the cobalt ferrite thin films and hence varying the cobalt cation distribution among the tetrahedral and octahedral sites and the strain state of the films, we are able to tune the symmetry and the magnitude of the magnetic anisotropy.

• Received 3 March 2000

DOI:https://doi.org/10.1103/PhysRevB.62.R779