Large Spin Hall Angle in Sputtered BiSb Topological Insulator on Top of Various Ferromagnets With In-Plane Magnetization for SOT Reader Application

A spin-orbit torque (SOT) reader using the inverse spin Hall effect was recently proposed as a candidate for magnetic recording beyond 4 Tbit/in2. However, SOT readers using conventional heavy metals have small output voltage and low signal-to-noise ratio (SNR) due to the small spin Hall angles of heavy metals. Demonstrated in this work is a large spin Hall angle of 2.6–5.1 in sputtered BiSb, a topological insulator, on top of various ferromagnets with in-plane magnetization. The spin Hall angle of BiSb is much larger than that of heavy metals, which is promising for SOT readers with large output and high SNR.