Single-shot dynamics of spin-orbit torque and spin transfer torque switching in three-terminal magnetic tunnel junctions

Abstract

Current-induced torques enable fast and efficient control of the state of magnetic tunnel junctions (MTJ). While switching dynamics has been extensively studied in spin transfer torque (STT) driven MTJ devices, less is known about the transient dynamics and actual reversal speed of individual switching events induced by spin-orbit torques (SOT). Our real-time single-shot measurements reveal that SOT switching unfolds by a stochastic two-step process involving the nucleation and propagation of a reversed domain. Timescales and statistical distributions of these processes differ significantly when compared to switching by STT. The stochastic nature of the switching dynamics can be minimized by the combined action of SOT, STT, and the voltage control of magnetic anisotropy, resulting in reproducible sub-nanosecond switching with a distribution of switching onsets and durations approaching 0.1 ns.