A conductive topological insulator with large spin Hall effect for ultralow power spin-orbit torque switching

摘要

Spin-orbit torque switching using the spin Hall effect in heavy metals and topological insulators has a great potential for ultralow power magnetoresistive random-access memory. To be competitive with conventional spin-transfer torque switching, a pure spin current source with a large spin Hall angle (θ_(SH) > 1) and high electrical conductivity (σ > 10~(5) Ω~(-1) m~(-1)) is required. Here we demonstrate such a pure spin current source: conductive topological insulator BiSb thin films with σ ≈ 2.5 × 10~(5) Ω~(-1) m~(-1), θ_(SH) ≈ 52 and spin Hall conductivity σ_(SH) ≈ 1.3 × 10~(7) [Formula: see text]Ω~(-1) m~(-1)at room temperature. We show that BiSb thin films can generate a very large spin-orbit field of 2.3 kOe MA~(-1) cm~(2)and a critical switching current density as low as 1.5 MA cm~(-2)in Bi_(0.9)Sb_(0.1)/MnGa bilayers, which underlines the potential of BiSb for industrial applications.