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

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 > 10⁵ 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 × 10⁵ Ω^-1 m^-1, θ_SH ≈ 52 and spin Hall conductivity σ_SH ≈ 1.3 × 10⁷ [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 cm² and a critical switching current density as low as 1.5 MA cm^-2 in Bi_0.9Sb_0.1/MnGa bilayers, which underlines the potential of BiSb for industrial applications.