Strong Spin-Orbit Interaction Induced in Graphene by Monolayer WS$_2$

TL;DR

This paper demonstrates that monolayer WS$_2$ induces a strong, anisotropic spin-orbit interaction in graphene, significantly surpassing the effect of bulk WS$_2$, with implications for spintronic applications.

Contribution

It provides the first direct comparison showing monolayer WS$_2$ induces stronger SOI in graphene than bulk WS$_2$, and characterizes the symmetry and magnitude of this interaction.

Findings

Monolayer WS$_2$ induces SOI > 10 meV in graphene.

The dominant SOI symmetry is $z$ $ ightarrow$ $-z$ symmetric.

Spin relaxation follows the Elliott-Yafet mechanism.

Abstract

We demonstrate strong anisotropic spin-orbit interaction (SOI) in graphene induced by monolayer WS$_2$. Direct comparison between graphene/monolayer WS$_2$ and graphene/bulk WS$_2$ system in magnetotransport measurements reveals that monolayer transition metal dichalcogenide (TMD) can induce much stronger SOI than bulk. Detailed theoretical analysis of the weak-antilocalization curves gives an estimated spin-orbit energy ($E_{\rm so}$) higher than 10 meV. The symmetry of the induced SOI is also discussed, and the dominant $z$ $\rightarrow$ $-z$ symmetric SOI can only explain the experimental results. Spin relaxation by the Elliot-Yafet (EY) mechanism and anomalous resistance increase with temperature close to the Dirac point indicates Kane-Mele (KM) SOI induced in graphene.