Experimental demonstration of voltage-gated spin-orbit torque switching in an antiferromagnet/ferromagnet structure

Efficient manipulation of magnetization is crucial for magnetic random-access memory (MRAM). Here we experimentally demonstrate spin-orbit-torque-driven (SOT-driven) magnetization switching of perpendicularly magnetized IrMn/CoFeB/MgO structures with the assist of a gate voltage. It is found that with the gate voltage changing from -0.6 to 0.6 V, the SOT critical switching current density Jc is reduced by 59%. Furthermore, the mechanism of voltage-induced Jc reduction is explored. We find that the dampinglike torque decreases with positive voltage, while the fieldlike torque shows a weak voltage dependence, which demonstrates that the voltage control of spin-orbit torque (VCSOT) effect has no positive effect on the reduction of Jc. In addition, a significant decrease of anisotropy energy is observed when a positive voltage is applied. These results indicate that both VCSOT effect and voltage control of magnetic anisotropy (VCMA) effect exist in voltage-gated SOT switching, while the VCMA effect plays a main role in reduction of Jc. This work shows low-power magnetization switching and helps to understand the mechanism of voltage-gated SOT switching.