Nanosecond ultralow power spin orbit torque magnetization switching driven by BiSb topological insulator

Topological insulators (TIs) are promising for spin–orbit torque (SOT) switching thanks to their giant spin Hall angle. SOT switching using TIs has been studied so far in the thermal activation regime by direct currents or relatively long pulse currents (≥10 ns). In this work, we studied SOT magnetization switching of (Pt/Co) multilayers with strong perpendicular magnetic anisotropy by the BiSb topological insulator in both thermal activation and fast switching regime with pulse width down to 1 ns. We reveal that the zero-Kelvin threshold switching current density $Jth0BiSb$ is 2.5 × 10⁶ and 4.1 × 10⁶ A/cm² for the thermal activation regime and fast switching regime in a 800 nm-wide Hall bar device via domain wall depining. From time-resolved measurements using 1 ns pulses, we find that the domain wall velocity is 430–470 m/s at J^BiSb = 1.6 × 10⁷–1.7 × 10⁷ A/cm². Our work demonstrates the potential of the BiSb thin film for ultralow power and fast operation of SOT-based spintronic devices.