Impact of surface oxidation on gilbert damping and inverse spin hall effect in SiO2/Ta/NiFe multilayers

• High spin mixing conductance: demonstrated high interfacial spin mixing conductance of −1.83(±0.05) × 1019 m -2 and a spin diffusion length (λ SD ) of 2.77±0.53 nm, which were derived from the Ta thickness-dependent effective damping measurements. • Non-equilibrium spin accumulation: significant reduction of Gilbert damping parameter of NiFe(10 nm)/Ta(t nm) sample (0.0074 ± 0.003) compared to bare NiFe(10 nm) sample (0.0121 ± 0.002) due to nonequilibrium spin accumulation at interface. • Anti-damping: formation of oxide layer NiO at surface of Ta (tnm)/NiFe(10 nm) can be accredited for the anti-damping. • High inverse spin hall voltage measurement and spin hall angle calculations: we measured the transverse voltage generated by spin-to-charge conversion due to the Inverse Spin hall Effect (ISHE) in Ta. From these measurements, a negative spin hall angle of −0.024 was calculated for the 7 nm Ta sample. Spin pumping in bilayer systems composed of ferromagnetic materials (FM) and heavy metals (HM) generates spin currents that can be detected by the inverse spin Hall effect (ISHE). Here, the reduction in Gilbert's damping ( α ) during spin pumping and the ISHE in the SiO 2 /Ta (tnm)/NiFe (10nm) bilayer system was observed. The value of α for SiO 2 /NiFe (10 nm) was determined to be 0.0121 ± 0.0003. However, for SiO 2 /Ta (t nm)/NiFe (10 nm), a consistently lower damping across all Ta thicknesses was observed, which could be due to non-equilibrium spin accumulation at the interface. Additionally, high interfacial spin mixing conductance values of -1.83(±0.05) × 10 19 m -2 and a spin diffusion length ( λ SD ) of 2.77±0.53 nm was obtained. Further high inverse spin Hall voltage was recorded and the spin Hall angle of -0.024 was calculated for the Ta 7 nm system.