Enhancement of Spin–Orbit Torque by Strain Engineering in SrRuO₃ Films

Abstract Complex oxides with 4d/5d transition metal ions, e.g., SrRuO 3 , usually possess strong spin–orbit coupling, which potentially leads to efficient charge‐spin interconversion. As the electrical transport property of SrRuO 3 can be readily tuned via structure control, it serves as a platform for studying the manipulation of charge‐spin interconversion. Here, a factor of twenty enhancement of spin–orbit torque (SOT) efficiency via strain engineering in a SrRuO 3 /Ni 81 Fe 19 bilayer is reported. The results show that an orthorhombic SrRuO 3 leads to a higher SOT efficiency than the tetragonal one. By changing the strain from compressive to tensile in the orthorhombic SrRuO 3 , the SOT efficiency can be increased from an average value of 0.04 to 0.89, corresponding to a change of spin Hall conductivity from 27 to 441 × ħ / e (S cm −1 ). The first‐principles calculations show that the intrinsic Berry curvature can give rise to a large spin Hall conductivity (SHC) via the strain control, which is consistent with the experimental observations. The results provide a route to further enhance the SOT efficiency in complex oxide‐based heterostructures, which will potentially promote the application of complex oxides in energy‐efficient spintronic devices.