Highly Efficient Room-Temperature Spin-Orbit-Torque Switching in a Van der Waals Heterostructure of Topological Insulator and Ferromagnet

Abstract

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 (qICS). Here, a vdW heterostructure is used consisting of atomically-thin layers of a bulk-insulating TI Sn-doped Bi1.1Sb0.9Te2S1 and a room-temperature ferromagnet Fe3GaTe2, to enhance the relative current ratio on the TSS up to approximate to 20%. The resulting qICS reaches approximate to 1.65 nm-1 and the critical current density Jc approximate to 0.9 x 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. Current-driven magnetization switching via spin-orbit torque is achieved at room temperature in a van der Waals heterostructure of a bulk-insulating topological insulator Sn-doped Bi1.1Sb0.9Te2S1 and a room temperature ferromagnet, Fe3GaTe2. By controlling the thickness of the constituent layers and maximizing the relative current ratio on the topological surface states, the highly efficient spin-orbit-torque operation is realized, surpassing the performance of most previous devices. image