Field-free Spin–Orbit Torque Perpendicular Magnetization Switching Induced by Metallic Multilayers

The realization of the all-electrical manipulation of perpendicular magnetization switching is essential for next-generation information storage technologies and spintronic devices. Current-induced spin-orbit torque (SOT) has attracted tremendous research interest. However, this approach usually relies on external magnetic field to achieve deterministic switching, which greatly limits SOT devices moving toward practical applications. Here, we report the measurement of SOT from the [Pt/Au] multilayer with composition gradient along the thickness direction. The multilayer exhibits a much larger SOT efficiency than pure Pt, and current-induced field-free magnetization switching has been realized in Co/[Pt/Au] heterostructures. Anomalous Hall resistance loop shift measurements indicate that the [Pt/Au] multilayer can produce spin current with