Spin-Orbit Interaction Induced in Graphene by Transition-Metal Dichalcogenides

TL;DR

This study demonstrates that transition-metal dichalcogenides can significantly enhance spin-orbit interaction in graphene, with monolayer WSe2 and WS2 inducing the strongest effects, which could enable quantum spin Hall states.

Contribution

It provides a systematic experimental analysis of how different TMDs induce varying strengths and types of spin-orbit interaction in graphene, highlighting the potential for realizing QSH states.

Findings

Monolayer WSe2 and WS2 induce stronger SOI than bulk counterparts.

Estimated SO scattering strength reaches up to 10 meV with certain TMDs.

Identifies the dominant spin relaxation mechanisms and symmetry of induced SOI.

Abstract

We report a systematic study on strong enhancement of spin-orbit interaction (SOI) in graphene driven by transition-metal dichalcogenides (TMDs). Low temperature magnetotoransport measurements of graphene proximitized to different TMDs (monolayer and bulk WSe$_2$, WS$_2$ and monolayer MoS$_2$) all exhibit weak antilocalization peaks, a signature of strong SOI induced in graphene. The amplitudes of the induced SOI are different for different materials and thickness, and we find that monolayer WSe$_2$ and WS$_2$ can induce much stronger SOI than bulk ones and also monolayer MoS$_2$. The estimated spin-orbit (SO) scattering strength for the former reaches $\sim$ 10 meV whereas for the latter it is around 1 meV or less. We also discuss the symmetry and type of the induced SOI in detail, especially focusing on the identification of intrinsic and valley-Zeeman (VZ) SOI via the dominant spin relaxation mechanism. Our findings offer insight on the possible realization of the quantum spin Hall (QSH) state in graphene.