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Proximity exchange induced gap opening and topological feature in graphene/1T'-MX2 (M = Mo,W; X = S,Se,Te) Dirac
Changsheng Song1, Wen Xiao1, Ping Lin1
1Department of Physics, Zhejiang Sci-Tech University, Hangzhou 310018, People's Republic of China.
Abstract:
By using first-principles calculations, we demonstrate the influence of proximity effect on the band structures of heterostructures formed by graphene stacking on a two dimensional (2D) topological insulator (TI) 1T'-MX2. The interlayer distance d between graphene and TI decreases with the enhancement of the intrinsic lattice anisotropy of 1T'-MX2, which determines different strength of the interlayer proximity interaction. The bandgap can be opened by the proximity exchange. The weak anisotropic symmetry of heterostructure (large d) only results in a small band gap (∼50 meV) in graphene/MoTe2. However, a large energy gap (up to ∼200 meV) can be obtained in graphene/MoS2, which is attributed to the inter-intralayer charge transfer due to the strong proximity interaction of the hetero-interface (small d). In addition, the 1T'-MX2 of heterostructure still possesses the topological feature of Z 2 = 1, since the graphene has a negligible effect on the band structure of the system.
