Exceptionally High, Strongly Temperature Dependent, Spin Hall Conductivity of SrRuO.

Spin-orbit torques (SOT) in thin film heterostructures originate from strong spin-orbit interactions (SOI) that, in the bulk, generate a spin current due either to extrinsic spin-dependent, skew, or/and side-jump scattering or to intrinsic Berry curvature in the conduction bands. While most SOT studies have focused on materials with heavy metal components, the oxide perovskite SrRuO has been predicted to have a pronounced Berry curvature. Through quantification of its spin current by the SOT exerted on an adjacent Co ferromagnetic layer, we determine that SrRuO has a strongly temperature ( T)-dependent spin Hall conductivity σ , increasing with the electrical conductivity, consistent with expected behavior of the intrinsic effect in the "dirty metal" regime. σ is very high at low T, e.g., σ > (ℏ/2 e)3 × 10 Ω m at 60 K, and is largely unaffected by the SrRuO ferromagnetic transition at T ≈ 150 K, which agrees with a recent theoretical determination that the intrinsic spin Hall effect is magnetization independent. Below T smaller nonstandard SOT components also develop associated with the magnetism of the oxide. Our results are consistent with the degree of RuO octahedral tilt being correlated with the strength of the SOI in this complex oxide, as predicted by recent theoretical work on strontium iridate. These results establish SrRuO as a very promising candidate material for implementing strong spintronics functionalities in oxide electronics.