Control of the Interfacial Exchange Coupling Energy in Pt/Co/ $\alpha$ -Cr $_{2}$ O

We investigated the control of the perpendicular exchange bias (PEB) in Pt/Co/α-Cr₂O₃ (0001) thin films that exhibit a unique temperature dependence of the PEB. Previously, we demonstrated that the onset of the PEB is explained by the competition between the interface coupling energy and the magnetic anisotropy energy in the α-Cr₂O₃ layer. Based on this finding, in this study, we investigated the influence of a Pt spacer layer at the Co/α-Cr₂O₃ interface to control the interface exchange coupling. By inserting a Pt spacer layer, the unidirectional magnetic anisotropy energy J_K was reduced because of the weakened exchange coupling between Co and α-Cr₂O₃. The weakened direct exchange coupling caused an increase in the onset temperature of J_K, resulting in a reduction in the α-Cr₂O₃ layer thickness necessary to maintain the PEB up to the Néel temperature. In addition, the change in the interface exchange coupling mechanism between Co and α-Cr₂O₃ is discussed with respect to the temperature dependence of J_K.