Ultralow-power spin-orbit torque magnetization switching in all-sputtered BiSb topological insulator–ferromagnet multilayers

摘要

Recently, we have shown that BiSb is a conductive topological insulator (TI) with a giant spin Hall angle (θ_(SH)～52) at room temperature, which is very attractive for spintronics applications, especially in spin-orbit-torque (SOT)-magnetic random access memory (MRAM). However, high quality and single-crystalline BiSb thin films require epitaxial growth in ultra-high vacuum by molecular beam epitaxy (MBE). For mass production, however, BiSb has to be fabricated under industrial conditions by physical vapor deposition techniques, which may yield different crystal quality and spin-charge conversion efficiency. Therefore, evaluation of BiSb deposited by sputtering technique on Si substrates is required as a first step toward ultralow-power SOT-MRAM with BiSb as the spin current source.