Concurrent observation of robust anti-damping torque and inverse spin Hall effect in Fe₇₅Co₂₅/Bi₂Te₃ multilayers

In this work, we made ferromagnet (FM) -Topological insulator (TI) heterostructures by depositing metallic FM Fe₇₅Co₂₅ (FeCo) epitaxial films capped with TI Bi₂Te₃ in an ultrahigh vacuum sputtering system. Contrary to the common observation of enhancement in Gilbert damping α on spin pumping, the multilayers of FeCo/Bi₂Te₃ exhibit a decrease in α with increase in Bi₂Te₃ thickness which is likely to be the effect of high anti-damping torque [1]. The quantification of room temperature spin-to-charge conversion has been made using two complementary techniques: ferromagnetic resonance (FMR) based inverse spin Hall effect (ISHE) measurement and femto-second light-pulse induced terahertz emission. Our results indicate that both FMR and ultrafast spin-current injection are promising complementary tools to investigate ISHE and high anti-damping torque.

[1] Emori, Satoru, et al." Applied Physics Letters 106.2 (2015): 022406.