Moiré Engineering of Spin–Orbit Torque by Twisted WS2 Homobilayers

Abstract

Artificial moiré superlattices created by stacking 2D crystals have emerged as a powerful platform with unprecedented material-engineering capabilities. While moiré superlattices are reported to host a number of novel quantum states, their potential for spintronic applications remains largely unexplored. Here, the effective manipulation of spin–orbit torque (SOT) is demonstrated using moiré superlattices in ferromagnetic devices comprised of twisted WS₂/WS₂ homobilayer (t-WS₂) and CoFe/Pt thin films by altering twisting angle (θ) and gate voltage. Notably, a substantial enhancement of up to 44.5% is observed in SOT conductivity at θ ≈ 8.3°. Furthermore, compared to the WS₂ monolayer and untwisted WS₂/WS₂ bilayers, the moiré superlattices in t-WS₂ enable a greater gate-voltage tunability of SOT conductivity. These results are related to the generation of the interfacial moiré magnetic field by the real-space Berry phase in moiré superlattices, which modulates the absorption of the spin-Hall current arising from Pt through the magnetic proximity effect. This study highlights the moiré physics as a new building block for designing enhanced spintronic devices.