Spin-orbit torques of three spin polarizations in magnetic trilayers

Abstract

Three spin polarizations of spin-orbit torques are theoretically available in ferromagnet/normal metal/ferromagnet trilayers. We report the quantification of spin-orbit torques of these spin polarizations via harmonic Hall voltage measurement. Furthermore, we show that using all three polarizations reduces the field-free spin-orbit torque (SOT) switching current of a perpendicular magnetization by employing a bottom ferromagnet with a tilted easy-axis in trilayer systems.