High spin Hall angle in BiSb topological insulator and perpendicularly magnetized CoFeB/MgO multilayers with metallic interfacial layers

Abstract

In this study, we investigate the spin Hall effect in heterostructures of Bi0.85Sb0.15 (10 nm) topological insulator/Ru(Ti)/Ta/Co20Fe60B20/MgO with perpendicular magnetic anisotropy. By optimizing the Ru (Ti) interfacial layer thickness as well as deposition condition of BiSb, we achieve a large effective spin Hall angle of 6.0 ± 0.1 and relatively high electrical conductivity of 1.5 × 105 Ω−1 m−1 at room temperature. We, then, demonstrate spin-orbit torque-induced magnetization switching driven by a small threshold current density of 1 × 106 Acm−2. Benchmarking shows that the writing power consumption of our stack is 2-3 orders smaller than that of heavy metals.