Ultralow Power Magnetization Switching by Non-Epitaxial Topological Insulator-Generated Spin-Orbit Torque

Topological insulators (TIs) with large spin Hall effect have potential applications for ultralow power consumption spintronic devices. However, the present methods for fabricating TIs mainly rely on epitaxial methods, which limits their mass production. Herein, perpendicular magnetized Pt/Co/(Bi1-x Sb x )(2)Te-3 (BST) heterostructures are prepared to measure the spin-orbit torque efficiency of BST fabricated by the conventional magnetron sputtering method, which shows large-scale wafer production ability. The Fermi levels and the topological surface states (TSSs) are modulated by the composition of Sb in BST. The effective damping-like spin Hall angle (theta SH eff ) is independent of the thickness of TIs. When the Fermi level is near the Dirac point, theta SH eff for these non-epitaxial heterostructures reaches its maximum value around 0.77, which is much larger than that of traditional ferromagnetic/heavy metal (FM/HM) heterostructures and quite close to that of the epitaxial TIs. This indicates that the TSS has the dominant contribution to theta SH eff . The large theta SH eff results in the small critical current density (J (c) approximate to 10(5) A cm(-2)) for fully switching the magnetization of Co, compared with FM/HM heterostructures with J (c) around 10(7) A cm(-2). This work paves the way for potential large-scale spintronic devices using low energy consumption non-epitaxial TIs.