Tuning Spin-orbit Coupling in Few-layer InSe

Manipulating the spin of electrons with the aid of Rashba spin-orbit coupling (SOC) is an indispensable element of spintronics. Electrostatically gating a material with strong Rashba SOC results in an effective magnetic field which in turn can be used to govern the spin of electrons. Hereupon we report the existence of the Rashba SOC in few-layer InSe; and its ability to be tuned electrostatically. We observed weak-antilocalization (WAL) effect in magnetotransport studies of InSe, which is indicative of strong SOC. The WAL effect was utilized to extract phase coherence length (42-63 nm) and spin-orbit relaxation length (40-51 nm). We also demonstrate gate-controlled Rashba SOC with Rashba coefficient changing from 1.03 to 1.28 (×10^-11 eVm). This SOC manipulation of InSe may serve pivotally in devising InSe-based 2D-spintronic devices in the future.