Tuning proximity-induced spin-orbit coupling in graphene/WSe$_{2}$ heterostructures

TL;DR

This study experimentally investigates how the twist angle and mechanical pressure influence proximity-induced spin-orbit coupling in graphene/WSe$_{2}$ heterostructures, confirming theoretical predictions and demonstrating tunability of SOC strength.

Contribution

The paper provides experimental validation of the twist angle dependence of SOC in graphene/WSe$_{2}$ heterostructures and shows tunability of SOC via mechanical pressure.

Findings

Strong twist angle dependence of SOC confirmed

SOC strength can be tuned by mechanical pressure

Experimental results agree with theoretical predictions

Abstract

Recently, proximity-induced spin-orbit coupling (SOC) has been observed in heterostructures consisting of monolayer graphene (ML-G) and transition metal dichalcogenides (TMDCs) such as WSe$_{2}$. Successful tuning of SOC in graphene/WSe$_{2}$ heterostructures by applying mechanical pressure and electric fields was also demonstrated in previous studies. In addition, theoretical calculations predicted a strong dependence of the proximity-induced SOC on the twist angle between graphene and TMDC. Here, we put these predictions to experimental test in ML-G/ML-WSe$_{2}$/hBN-heterostructures, where the twist angle is determined by aligning fractured edges, and by crystallographic etching of graphene. By performing weak anti-localization measurements, we determine the strength of the Rasbha-type SOC ($\lambda_\mathrm{R}$) and the valley-Zeeman-type SOC ($\lambda_\mathrm{VZ}$). Our experiments confirm a strong twist angle dependence of the proximity-induced SOC in agreement with theoretical predictions. Finally, we demonstrate the tunability of the SOC strength via mechanical pressure, which is in agreement with earlier findings.