Trivial and inverted Dirac bands and the emergence of quantum spin Hall states in graphene on transition-metal dichalcogenides

Gmitra, Martin and Kochan, Denis and Hoegl, Petra and Fabian, Jaroslav (2016) Trivial and inverted Dirac bands and the emergence of quantum spin Hall states in graphene on transition-metal dichalcogenides. PHYSICAL REVIEW B, 93 (15): 155104. ISSN 2469-9950, 2469-9969

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Abstract

Proximity orbital and spin-orbital effects of graphene on monolayer transition-metal dichalcogenides (TMDCs) are investigated from first-principles. The Dirac band structure of graphene is found to lie within the semiconducting gap of TMDCs for sulfides and selenides, while it merges with the valence band for tellurides. In the former case, the proximity-induced staggered potential gaps and spin-orbit couplings (all on the meV scale) of the Dirac electrons are established by fitting to a phenomenological effective Hamiltonian. While graphene on MoS2, MoSe2, and WS2 has a topologically trivial band structure, graphene on WSe2 exhibits inverted bands. Using a realistic tight-binding model we find topologically protected helical edge states for graphene zigzag nanoribbons on WSe2, demonstrating the quantum spin Hall effect. This model also features "half-topological states," which are protected against time-reversal disorder on one edge only.

Item Type: Article
Uncontrolled Keywords: ;
Subjects: 500 Science > 530 Physics
Divisions: Physics > Institute of Theroretical Physics
Depositing User: Dr. Gernot Deinzer
Date Deposited: 18 Mar 2019 10:03
Last Modified: 18 Mar 2019 10:03
URI: https://pred.uni-regensburg.de/id/eprint/3092

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