Switching of perpendicular magnetization by spin–orbit torques in the absence of external magnetic fields

Abstract

Magnetization switching by current-induced spin–orbit torques is of great interest due to its potential applications in ultralow-power memory and logic devices. The switching of ferromagnets with perpendicular magnetization is of particular technological relevance. However, in such materials, the presence of an in-plane external magnetic field is typically required to assist spin–orbit torque-driven switching and this is an obstacle for practical applications. Here, we report the switching of out-of-plane magnetized Ta/Co₂₀Fe₆₀B₂₀/TaO_x structures by spin–orbit torques driven by in-plane currents, without the need for any external magnetic fields. This is achieved by introducing a lateral structural asymmetry into our devices, which gives rise to a new field-like spin–orbit torque when in-plane current flows in these structures. The direction of the current-induced effective field corresponding to this field-like spin–orbit torque is out-of-plane, facilitating the switching of perpendicular magnets.