Strong electron-hole symmetric Rashba spin-orbit coupling in graphene/monolayer transition metal dichalcogenide heterostructures*

Despite its extremely weak intrinsic spin-orbit coupling (SOC), graphene has been shown to acquire considerable SOC by proximity coupling with exfoliated transition metal dichalcogenides (TMDs). I will present our results of strong induced Rashba SOC in graphene that is proximity coupled to a monolayer of MoS$_{\mathrm{2}}$ and WSe$_{\mathrm{2}}$ grown by chemical-vapor deposition with drastically different Fermi level positions. We observed strong induced graphene SOC that manifests itself in a pronounced weak-antilocalization (WAL) effect in the graphene magnetoconductance. The spin-relaxation rate extracted from the WAL analysis varies linearly with the momentum scattering time and is independent of the carrier type. This indicates a dominantly Dyakonov-Perel spin-relaxation mechanism caused by the induced Rashba SOC. Our analysis yields a Rashba SOC energy of $\sim $1.5 meV in graphene/WSe$_{\mathrm{2}}$ and $\sim $0.9 meV in graphene/MoS$_{\mathrm{2}}$. The nearly electron-hole symmetric nature of the induced Rashba SOC provides a clue to possible underlying SOC mechanisms.