Field-free highly efficient spin-orbit torque switching in Fe3GaTe2 at room temperature enabled by a unique distorted crystal symmetry of WTe2

Spin-orbit torque (SOT) is a highly viable mechanism for achieving low-energy and high-speed switching in spintronic devices. Two-dimensional (2D) van der Waals (vdW) materials and their heterostructures have proven their scalability and energy effectiveness for device operation. Here, we demonstrate that SOT can be robustly realized in a heterostructure composed of the 2D-vdW ferromagnetic material (FM) Fe3GaTe2 (FGaT) and the 2D-vdW topological semimetal WTe2 at room temperature. The anisotropic Fermi surface originating from the uniquely reduced crystal symmetry of WTe2 enables field-free deterministic SOT switching. We report an unprecedentedly low threshold switching current density of 6.5 × 109 A m−2 at zero field and a spin Hall angle (θSH) of 8.5. These results demonstrate a nearly 100-fold improvement in device performance over all previously reported 3D heavy metal (HM)/FM systems, supported by a second harmonic-modulated nonlinear signal measurement implemented to ensure SOT analysis and reliability. The spin Hall conductivity (σSH) and the switching power density (Psw) reported are about 1.3 × 106 S m−1 and 0.33 × 1015 W m−3, respectively, supporting the efficient device performance at low power consumption. Our result highlights that Fe3GaTe2, coupled with the strong spin–orbit coupling and low crystal symmetry of WTe2, in the form of 2D-vdW heterostructure (WTe2/Fe3GaTe2), offers a promising platform for generating substantial torque on magnetization at room temperature. This leads to more efficient and easier switching, paving the way for developing next-generation, highly advanced, room-temperature spin-electronic devices.