Voltage-driven reversible control of orbital torque in perpendicularly magnetized heterostructures

Orbital current in light metals has attracted considerable attention as an alternative tool to switch the magnetization of ferromagnets. However, the manipulation of orbital torque efficiency, which is a key aspect of novel spin-orbitronic devices, remains a challenge. Here, the reversible modulation of orbital torque at room temperature is demonstrated in perpendicularly magnetized Ta/Pt/Co/Cu–CuOx/MoOx Hall bar devices. By applying a negative electric field, the orbital torque efficiency of a device with a Cu–CuOx thickness of 3 nm can be significantly enhanced by a factor of ∼4.64. This outstanding result is attributed to the applied electric fields driving the migration of oxygen ions, which controls the distance between the Cu/CuOx interface and the Co layer, as well as the formation or reduction of an antiferromagnetic CoOx layer at the Co surface. Consequently, the injection efficiency of the orbital current is controlled. In addition, the critical magnetization switching current density is reduced by ∼36% by applying an electric field. These findings provide a pathway for implementing electrically driven magnetization switching in potential applications while also opening new avenues for the development of spin-orbitronic devices.