Room temperature spin-orbit torque switching induced by a topological insulator

The strongly spin-momentum coupled electronic states in topological insulators (TI) have been extensively pursued to realize efficient magnetic switching. However, previous studies show large discrepancy of the charge-spin conversion efficiency. Moreover, current-induced magnetic switching with TI can only be observed at cryogenic temperatures. Here we report spin-orbit torque (SOT) switching in a TI/ferrimagnet heterostructure with perpendicular magnetic anisotropy at room temperature. The low switching current density (~ 3 × 10⁶ A/cm²) provides definitive proof of the high SOT efficiency from TI. The SOT efficiency is measured by the current-induced shift of the Hall resistance-vs-magnetic field hysteresis loops, which is consistent with the model of the current-induced Néel-type domain wall expansion. The obtained effective spin Hall angle of TI is substantially larger than the previously studied heavy metals. Furthermore, we calculate the power consumption for switching a ferromagnetic layer with TI, Pt, and Ta, and find that the magnetization switching with TI presents much higher energy efficiency than the heavy metals. Our results demonstrate the robustness of TI as an SOT switching material and provide an avenue towards applicable TI-based spintronic devices.