A highly efficient spin Hall effect generator of spin currents

Current-induced spin-orbit torques (SOTs) in heavy metal/ferromagnet (HM/FM) multilayers, where the spin Hall effect (SHE) in the HM layer is the dominant spin current source, can play an efficient role in manipulating magnetization at the nanoscale. Despite extensive efforts and recent demonstrations of fast SOT switching of in-plane magnetized MTJs, the energy efficiency of SOT devices based on the conventional spin Hall materials (e.g. W, Pt, and Ta) has been limited by a relatively small spin Hall angle, or a high resistivity of the HM, and/or damping enhancement due to strong spin memory loss at the HM/FM interface. On the other hand, for perpendicularly magnetized systems the DMI at the HM/FM interface requires an external magnetic field, or its equivalent, that is larger than the DMI field applied along the bias current direction in order to switch the magnetization, which leads to device complexity. Here we will report a highly efficient SHE spin current generator which simultaneously shows a giant ant-damping spin-torque efficiency of ~0.35, a relatively low resistivity of ~ 83 μΩ cm, reduced spin memory loss at the FM (e.g. FeCoB) interface, and as well a DMI that is tunable, to zero if desired.