Strain induced Magnetic Anisotropy in Cobalt Vanadate Thin Films

Cobalt Vanadate (CoV₂O₄) is a cubic normal spinel that displays interplay between orbital, magnetic, and structural properties. One aspect of the material is its 90 K tetragonal distortion resulting in a noncollinear ferrimagnetic phase, as evidenced by neutron scattering studies¹. To study the effects of structural distortion, CoV₂O₄ is grown on an (001) SrTiO₃ substrate, inducing an in-plane compressive strain that results in an orthorhombic unit cell. For the thin films, magnetometry and neutron scattering measurements² show that its magnetic easy axis changes from out-of-plane to in-plane upon cooling through 90 K. To explore the temperature evolution of the magnetic anisotropic surface, torque magnetometry is utilized. Of key interest is the large change in magnetic anisotropy at 90 K, below which the field needed to saturate the magnetization along the out-of-plane hard axis increases by an order of magnitude.