Acoustic Ferromagnetic Resonance Assisted Spin-Torque Switching of Perpendicular MTJs

Resonant Surface Acoustic Wave (SAW) assisted Spin Transfer Torque (STT) can drive the magnetization of a perpendicular magnetic tunnel junction (p-MTJ) and write bits with an order of magnitude lower energy dissipation compared to the conventional STT current approach [1]. Simulations show that such acoustically driven ferromagnetic resonance (FMR) results in the magnetization precessing in a cone with large deflections relative to the perpendicular direction. The larger the precession angle, the lower the STT current required for switching the magnetization. While our prior simulations [1] of such magnetization dynamics were based on macro-spin assumptions, here we will perform micromagnetic simulations to study incoherent switching in the presence of room temperature thermal noise as well as incorporate realistic effects such as material inhomogeneity, grains, surface roughness and lithographic imperfections. The ramification of such incoherency in magnetization dynamics on the switching error will be discussed. Preliminary experimental work will also be presented.

Reference:
[1]. Roe, A., et al., Applied Physics Letters, 115(11), 112405, 2019.