Effect of strain on the magnetic anisotropy in the epitaxial magnetic thin films

A phenomenological thermodynamic theory of magnetic thin films epitaxially grown on cubic substrates is developed by considering the thermodynamic potential, which corresponds to the actual mechanical boundary conditions. For clamped magnetic thin films with two-dimension strains, the study reveals that the magnitudes of remanent magnetization Mr and coercive field Hc are dependent on the strain induced by the lattice mismatch. The tensile strain can significantly enhance the out-of-plane magnetization with a larger coercivity, while the compressive strain makes correspondingly thin films exhibit an opposite in-plane magnetic anisotropy. Our analysis provides a profound understanding of magnetic anisotropy mechanism and the relationship with lattice strain in the epitaxial magnetic thin film.