Ultrahigh efficient spin-orbit torque magnetization switching in all-sputtered topological insulator - ferromagnet multilayers

Abstract

Spin-orbit torque (SOT) magnetization switching of ferromagnets with large perpendicular magnetic anisotropy has a great potential for the next-generation non-volatile magnetoresistive random-access memory (MRAM). It requires a high-performance pure spin current source with a large spin Hall angle and high electrical conductivity, which can be fabricated by a mass production technique. In this work, we demonstrate ultrahigh efficient and robust SOT magnetization switching in all-sputtered BiSb topological insulator - perpendicularly magnetized Co/Pt multilayers. Despite fabricated by the industry-friendly magnetron sputtering instead of the laboratory molecular beam epitaxy, the topological insulator layer, BiSb, shows a large spin Hall angle of $\theta$${}_{SH}$ = 12.3 and high electrical conductivity of $\sigma$ = 1.5x$10^5$ ${\Omega }^{-1}$m${}^{-1}$. Our results demonstrate the mass production capability of BiSb topological insulator for implementation of ultralow power SOT-MRAM and other SOT-based spintronic devices.