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) Fe 3 GaTe 2 (FGaT) and the 2D-vdW topological semimetal WTe 2 at room temperature. The anisotropic Fermi surface originating from the uniquely reduced crystal symmetry of WTe 2 enables field-free deterministic SOT switching. We report an unprecedentedly low threshold switching current density of 6.5 × 10 9 A m −2 at zero field and a spin Hall angle ( θ S H ) 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 ( σ S H ) and the switching power density ( P s w ) reported are about 1.3 × 10 6 S m −1 and 0.33 × 10 15 W m −3 , respectively, supporting the efficient device performance at low power consumption. Our result highlights that Fe 3 GaTe 2 , coupled with the strong spin–orbit coupling and low crystal symmetry of WTe 2 , in the form of 2D-vdW heterostructure (WTe 2 /Fe 3 GaTe 2 ), 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.