Stress-tailoring magnetic anisotropy of V2O3/Ni bilayers

We report on a temperature-driven reversible change of the in-plane magnetic anisotropy of V2O3/Ni bilayers. This is caused by the rhombohedral to monoclinic structural phase transition of V2O3 at T-C = 160 K. The in-plane magnetic anisotropy is uniaxial above T-C, but as the bilayer is cooled through the structural phase transition, a secondary magnetic easy axis emerges. Ferromagnetic resonance measurements show that this change in magnetic anisotropy is reversible with temperature. We identify two structural properties of the V2O3/Ni bilayers affecting the in-plane magnetic anisotropy: (1) a growth-induced uniaxial magnetic anisotropy associated with steplike terraces in the bilayer microstructure and (2) a low-temperature strain-induced biaxial anisotropy associated with the V2O3 structural phase transition. Magnetoresistance measurements corroborate the change in magnetic anisotropy across the structural transition and suggest that the negative magnetostriction of Ni leads to the emergence of a strain-induced easy axis. This shows that a temperature-dependent structural transition in V2O3 may be used to tune the magnetic anisotropy in an adjacent ferromagnetic thin film.