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 [1]. 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 3-terminal MTJ devices [2,3]. 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 SOT switching assisted by voltage control of magnetic anisotropy (VCMA) and STT leads to reproducible sub-ns switching with a spread of the cumulative switching time smaller than 0.2 ns and a critical switching energy comparable to STT. Our measurements unravel the combined impact of SOT, STT, and VCMA in determining the switching speed and efficiency of MTJ devices. Opportunities for scalable all-electric magnetic memories and memory-in-logic applications will be discussed [4].

[1] Current-induced spin-orbit torques in ferromagnetic and antiferromagnetic systems, A. Manchon et al., Rev. Mod. Phys. 91, 035004 (2019).

[2] Single-shot dynamics of spin-orbit torque and spin transfer torque switching in 3-terminal magnetic tunnel junctions, E. Grimaldi et al., Nat. Nanotech. 15, 111 (2020).

[3] Field-​free switching of magnetic tunnel junctions driven by spin–orbit torques at sub-​ns timescales, V. Krizakova et al., Appl. Phys. Lett. 116, 232406 (2020).

[4] Current-driven magnetic domain-wall logic, Z. Luo et al., Nature 579, 214 (2020).