Samsung Advanced Institute of Technology

All-Van der Waals (vdW)-material-based heterostructures with atomically sharp interfaces offer a versatile platform for high-performing spintronic functionalities at room temperature. One of the key components is vdW topological insulators (TIs), which can produce a strong spin-orbit-torque (SOT) through the spin-momentum locking of their topological surface state (TSS). However, the relatively low conductance of the TSS introduces a current leakage problem through the bulk states of the TI or the adjacent ferromagnetic metal layers, reducing the interfacial charge-to-spin conversion efficiency (q_ICS). Here we used a van der Waals (vdW) heterostructure consisting of atomically-thin layers of a bulk-insulating topological insulator Sn-doped Bi_1.1Sb_0.9Te₂S₁ and a room-temperature ferromagnet Fe₃GaTe_2, to enhance the relative current ratio on the TSS up to ~ 20%. The resulting q_ICS reaches ~ 1.65 nm^-1 and the critical current density J_c ~ 0.9 ´ 10⁶ Acm^-2 at 300 K, surpassing the performance of TI-based and heavy-metal-based SOT devices. These findings demonstrate that an all-vdW heterostructure with thickness optimization offers a promising platform for efficient current-controlled magnetization switching at room temperature.