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

TL;DR

This study provides time-resolved electrical measurements of magnetization switching in three-terminal magnetic tunnel junctions, revealing a stochastic two-step process for SOT-driven switching and demonstrating sub-nanosecond reproducible switching through combined effects.

Contribution

It introduces all-electrical time-resolved measurements of SOT switching in MTJs and uncovers the stochastic two-step process distinct from STT, with implications for faster memory devices.

Findings

SOT switching involves a stochastic two-step process with domain nucleation and propagation.

Combined SOT, STT, and VCMA enable sub-ns reproducible switching.

Switching times have a spread smaller than 0.2 ns.

Abstract

Current-induced spin-transfer torques (STT) and spin-orbit torques (SOT) enable the electrical switching of magnetic tunnel junctions (MTJs) in nonvolatile magnetic random access memories. In order to develop faster memory devices, an improvement of the timescales underlying the current driven magnetization dynamics is required. Here we report all-electrical time-resolved measurements of magnetization reversal driven by SOT in a three-terminal MTJ device. Single-shot measurements of the MTJ resistance during current injection reveal that SOT switching involves a stochastic two-step process consisting of a domain nucleation time and propagation time, which have different genesis, timescales, and statistical distributions compared to STT switching. We further show that the combination of SOT, STT, and voltage control of magnetic anisotropy (VCMA) leads to reproducible sub-ns switching with a spread of the cumulative switching time smaller than 0.2 ns. Our measurements unravel the combined impact of SOT, STT, and VCMA in determining the switching speed and efficiency of MTJ devices.