Interface Magnetism of $\hbox {Au/Co/Cr}_{2}\hbox {O}_{3}(0001)$ Epitaxial Film With Perpendicular Magnetic Anisotropy and Perpendicular Exchange Bias

We have investigated interface magnetism of Au-capped ultrathin Co film grown on antiferromagnetic Cr₂O₃(0001) thin film. In particular, perpendicular magnetic anisotropy and perpendicular exchange bias are investigated. To strengthen the analysis, structural investigations are also conducted. Ultrathin Co film shows both perpendicular magnetic anisotropy and perpendicular exchange bias. Perpendicular magnetic anisotropy is mainly caused by Au capping layer. However, Co/Cr₂O₃ interface also affects the perpendicular magnetic anisotropy through the collinear exchange coupling of Co spin and Cr spin. The collinear exchange coupling gives rise to the perpendicular exchange bias. This is explained by aligned Cr spin direction owing to epitaxial growth and small lattice misfit.