Acoustically assisted energy efficient field free spin orbit torque switching of out of plane nanomagnet

Abstract

Deterministic spin orbit torque (SOT) magnetization switching of the perpendicular magnetic anisotropy structures requires an external magnetic field, which is unsuitable for on-chip applications. Various approaches are there to debar the external magnetic field requirement. In this work, we use static stress, which can generate a virtual magnetic field via magnetoelastic coupling. We show that this field can be used for deterministic magnetization switching. In our simulations, we use an antiferromagnetic material for generating the SOT and exchange bias field and avail the benefits of the field like torque (FLT). With the exclusion of thermal noise, this reduces the threshold current density from 114 to 36 MA/cm2, thus mitigating the energy dissipation by more than nine times. To study the effect of thermal noise, we simulate 500 trajectories and find out the switching probability. We perform simulations to study the effects of current density, stress, pulse width, and FLT on the switching probability in great details. Our simulation results show that we can get sub-ns switching with a probability of 0.99 requiring only 45.5 fJ of energy dissipation. This can be very attractive for artificial neural network kind of applications.