Enhanced spin accumulation in metallic bilayers with opposite spin Hall angles

Spin accumulation can be generated via the spin Hall effect in a nonmagnetic material. It was previously found that spin accumulation and associated spintronic phenomena are attenuated in metallic bilayer with opposite spin angles. Here, we investigate the spin Hall magnetoresistance (SMR) in Pt/Y3Fe5O12 (YIG) with a thin W capping layer, in which W and Pt have opposite spin Hall angles. We find an increase of the SMR ratio with a W capping layer thinner than 1.0 nm. According to theoretical simulation, we attribute this phenomenon to the enhancement of the spin accumulation at the Pt/YIG interface, opposite to previous observations. Our findings provide a new approach for generating spin accumulation and associated pure spin current intensity for spintronic applications.