Giant Spin Hall Effect in Cu-Tb Alloy Thin Films.

We report the giant spin-current generation in CuTb alloys arising from the spin Hall effect. The maximum spin Hall angle from our CuTb-based magnetic heterostructures was found to be -0.35±0.02 for CuTb. We find that the contribution of skew scattering is larger than side jump for lower Tb concentrations (<14.9%), while the converse is true for higher Tb concentrations. Additionally, we also studied the Gilbert damping parameter, spin diffusion length and spin mixing conductance. Interfacial spin transparency is derived as 0.55±0.03 for theCuTb interface. The spin diffusion length and spin mixing conductance of the CuTb alloy are λ = 2.5±0.3 nm and G= (24.2±1.0) × 1015 cm, respectively. Our results pave a way for Rare-earth metals to be used as a spin Hall material in highly efficient SOT devices.