Tuning Rashba Spin-Orbit Coupling in Gated Multilayer InSe

TL;DR

This paper demonstrates the electrostatic tunability of Rashba spin-orbit coupling in multilayer InSe, showing a gate-controlled transition from weak localization to weak antilocalization, with implications for spintronic device development.

Contribution

It provides experimental evidence and analysis of gate-tunable Rashba SOC in InSe, revealing nonlinear behavior and saturation effects relevant for spintronics applications.

Findings

Gate voltage induces a crossover from WL to WAL in InSe.

Rashba SOC strength can be electrostatically tuned and saturates at high gate voltages.

The saturation is due to increased electronic density of states affecting the electric field.

Abstract

Manipulating the electron spin with the aid of spin-orbit coupling (SOC) is an indispensable element of spintronics. Electrostatically gating a material with strong SOC results in an effective magnetic field which can in turn be used to govern the electron spin. In this work, we report the existence and electrostatic tunability of Rashba SOC in multilayer InSe. We observed a gate-voltage-tuned crossover from weak localization (WL) to weak antilocalization (WAL) effect in quantum transport studies of InSe, which suggests an increasing SOC strength. Quantitative analyses of magneto-transport studies and energy band diagram calculations provide strong evidence for the predominance of Rashba SOC in electrostatically gated InSe. Furthermore, we attribute the tendency of the SOC strength to saturate at high gate voltages to the increased electronic density of states-induced saturation of the electric field experienced by the electrons in the InSe layer. This explanation of nonlinear gate voltage control of Rashba SOC can be generalized to other electrostatically gated semiconductor nanomaterials in which a similar tendency of spin-orbit length saturation was observed (e.g. nanowire field effect transistors), and is thus of broad implications in spintronics. Identifying and controlling the Rashba SOC in InSe may serve pivotally in devising III-VI semiconductor-based spintronic devices in the future.