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

Abstract

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). Here we demonstrate strong induced Rashba SOC in graphene that is proximity coupled to a monolayer TMD film, MoS2 or WSe2, grown by chemical vapor deposition with drastically different Fermi level positions. Graphene/TMD heterostructures are fabricated with a pickup-transfer technique utilizing hexagonal boron nitride, which serves as a flat template to promote intimate contact and therefore a strong interfacial interaction between TMD and graphene as evidenced by quenching of the TMD photoluminescence. We observe strong induced graphene SOC that manifests itself in a pronounced weak anti-localization (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 ~1.5 meV in graphene/WSe2 and ~0.9 meV in graphene/MoS2, respectively. The nearly electron-hole symmetric nature of the induced Rashba SOC provides a clue to possible underlying SOC mechanisms.

References in corpus (9)

• Electric Field Effect in Atomically Thin Carbon Films
• The Valley Hall Effect in MoS2 Transistors
• Charged Impurity Scattering in Graphene
• Intrinsic and Rashba Spin-orbit Interactions in Graphene Sheets
• Quantum Anomalous Hall Effect in Graphene from Rashba and Exchange Effects
• Proximity-induced ferromagnetism in graphene revealed by anomalous Hall effect
• Spin-Orbit Proximity Effect in Graphene
• Weak localisation in graphene flakes
• Tunable spin-orbit coupling and symmetry-protected edge states in graphene/WS${}_2$

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• Ultralong 100 ns Spin Relaxation Time in Graphite at Room Temperature
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• Weak localization as probe of spin-orbit-induced spin-split bands in bilayer graphene proximity coupled to WSe${}_2$
• Unprecedented Spin-Lifetime of Itinerant Electrons in Natural Graphite Crystals
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