Conductive BiSb topological insulator with colossal spin Hall effect for ultra-low power spin-orbit-torque switching

摘要

We report on epitaxial crystal growth and spin Hall effect in BiSb topological insulator thin films. We show that BiSb thin films with conductivity as high as σ ~ 2.5*10~5 Ω~(-1)m~(-1) can be epitaxially grown on GaAs(111)A substrate. Meanwhile, evaluation of spin-orbit-torque in Bi_(0.9)Sb_(0.1)/MnGa bi-layers reveals a colossal spin Hall angle of θ_(SH) ~ 52 and a spin Hall conductivity σ_(SH) ~ 1.3* 10~7 h/2e Ω~(-1)m~(-1) at room temperature. We demonstrate that BiSb thin films can generate a colossal spin-orbit field of 2.3 kOe/(MA/cm~2) and a critical switching current density as low as 1.5 MA/cm~2 in Bi_(0.9)Sb_(0.1)/MnGa bi-layers. BiSb is the best candidate for the first industrial application of topological insulators.