Ultra-low-power switching of IrMn/CoFeB/MgO structure with voltage-controlled spin-orbit torque

How to efficiently manipulate magnetization remains one of the key challenges for spintronic devices and magnetic random-access memories[1-3]. Here we experimentally demonstrate the ultra-low-power and field-free switching of perpendicular magnetization by a combination of spin-orbit torque (SOT) and voltage-controlled magnetic anisotropy effect. Firstly, field-free SOT switching is achieved with the aid of an in-plane exchange bias (EB) generated in the perpendicularly magnetized IrMn/CoFeB/MgO structure. Then we explore the VCMA effect and observed a clear reduction of perpendicular magnetic anisotropy (PMA) when a gate voltage is applied. A VCMA coefficient of 35 fJ/Vm is obtained in this structure, comparable to that of the Ta/CoFeB/MgO structure. By applying a gate voltage of 0.6 V on this film, the SOT switching current can be significantly reduced, resulting in a critical switching current of 6.2 MA/cm². Finally, an ultra-low-power and high-density spintronic memory array based on voltage-controlled SOT is proposed and demonstrated by both experiments and hybrid CMOS/MTJ simulations.
[1] S. Peng et al., Adv. Electron. Mater. 5, 1900134 (2019).
[2] M. Wang et al., Nat. Electron. 1, 582 (2018).
[3] S. Peng et al., Appl. Phys. Lett. 110, 072403 (2017).