Gate-tunable spin galvanic effect in topological insulator–graphene heterostructures

Unique electronic spin textures in topological states of matter are promising for emerging spintronic technologies (Nano Letters 15, 12, 7976 (2015), Phys. Rev. B 97, 125414 (2018)). Here we integrate topological insulator (TI) in van der Waals heterostructures with graphene to engineer proximity-induced spin-orbit coupling (Science Advances, 4, 9, eaat9349 (2018)) and charge-spin conversion (Nature Communication 11, 3657 (2020)) phenomena. In these heterostructures, we experimentally demonstrate a gate-tunable Rashba-Edelstein effect at room temperature, allowing for efficient conversion of a non-equilibrium spin polarization into a transverse charge current (Nature Communication 11, 3657 (2020)). Importantly, using a gate voltage, we reveal a strong electric field tunability of both amplitude and sign of the spin-galvanic signal. These findings provide an efficient route for realizing all-electrical and gate-tunable spin signals using TIs and graphene in heterostructures.