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

Complex oxides with 4d/5d transition metal ions, e.g., SrRuO3, usually possess strong spin-orbit coupling, which potentially leads to efficient charge-spin interconversion. As the electrical transport property of SrRuO3 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 SrRuO3/Ni81Fe19 bilayer is reported. The results show that an orthorhombic SrRuO3 leads to a higher SOT efficiency than the tetragonal one. By changing the strain from compressive to tensile in the orthorhombic SrRuO3, 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 x h/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.

Automated summary

Strain engineering in a SrRuO3/Ni81Fe19 bilayer can enhance spin-orbit torque (SOT) efficiency by a factor of twenty, with orthorhombic SrRuO3 showing higher efficiency than tetragonal. The results suggest that changing the strain in SrRuO3 can significantly increase the spin Hall conductivity, providing a pathway to enhance SOT efficiency in complex oxide-based heterostructures.