Topological Surface States-Induced Perpendicular Magnetization Switching in Pt/Co/Bi2Se3 Heterostructures

Recently, the topological insulators (TIs) with topological surface states (TSS) exhibiting large spin-orbit torques (SOTs) in topological insulators/ferromagnetic (TIs/FM) systems have been a hot spot research in spintronics. Herein, the effective spin Hall angles () in perpendicularly magnetized Pt/Co/Bi2Se3 stacks with different thicknesses of the Bi2Se3 layers are investigated by the harmonic Hall resistance measurements. The results show that the for the TIs/FM heterostructures is substantially larger than the previously reported heavy metal/ferromagnetic (HM/FM). Moreover, keeps constant with the value around 0.35 in Pt/Co/Bi2Se3 stacks with the variation of the thickness of Bi2Se3 from 3.0 to 15.0 nm, indicating that the SOTs are mainly derived from the contribution of the TSS of Bi2Se3 rather than the interfacial Rashba effect and/or bulk spin Hall effect. The results confirm that TIs with unique spintronic texture can play a crucial role in spintronics applications.