Highly Efficient Spin-Orbit Torque Switching in a Topological Insulator/Chromium Telluride Heterostructure with Opposite Berry Curvature

Abstract

Energy-efficient magnetization switching by current-induced spin-orbit torques drives the application of spintronics in memory and neural networks. Given the intrinsic strong spin-orbit coupling, topological insulators (TI) with spin-momentum locking are expected to be promising candidates for generating a significant spin-orbit torque compared to the heavy metal system. To achieve high charge-to-spin conversion efficiency, it is imperative to incorporate a ferromagnetic layer with low conductivity. In this study, a high spin-torque efficiency (β_L = 12.9 × 10⁻⁶mT A⁻¹cm²) and spin Hall conductivity (${\sigma }_{SH}=4.8\times {10}^6\frac{\hslash }{2e}{\mathrm{\Omega }}^{-1}{\mathrm{m}}^{-1}$) are reported as being observed at 80 K in a Cr₂Te₃/(Bi_0.5Sb_0.5)₂Te₃ bilayer. The magnetization switching induced by spin-orbit torque in a Cr₂Te₃/(Bi_0.5Sb_0.5)₂Te₃ bilayer is observed. It is demonstrated that the hump-like feature in the anomalous Hall effect (AHE) resistance curve can be attributed to the presence of two magnetic phases in compressively strained chromium telluride grown on a c-Al₂O₃ substrate using molecular beam epitaxy (MBE). The work holds the promise of propelling efficiency advancements in spintronic applications that leverage the unique properties of topological insulators.