标题： 平凡和反向狄拉克能带，以及在过渡金属二硫化物上的石墨烯中量子自旋霍尔态的出现 显示英文标题

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

摘要： 石墨烯与单层过渡金属二硫属化合物（TMDCs）的邻近轨道和自旋-轨道效应是从第一性原理出发进行研究的。 发现石墨烯的狄拉克能带结构位于硫化物和硒化物的半导体带隙内，而对于碲化物则与价带合并。 在前一种情况下，通过拟合到一个现象学的有效哈密顿量，建立了对狄拉克电子的邻近诱导的阶梯势能隙和自旋-轨道耦合（都在毫电子伏特量级）。 虽然石墨烯在MoS$_2$、MoSe$_2$和WS$_2$上具有拓扑平凡的能带结构，但石墨烯在WSe$_2$上表现出反向能带。 使用一个现实的紧束缚模型，我们发现石墨烯在WSe$_2$上的锯齿形纳米带具有拓扑保护的螺旋边缘态，证明了量子自旋霍尔效应。 该模型还具有“半拓扑态”，这些态仅在一个边缘上对抗时间反演无序。 显示英文摘要

摘要： 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 MoS$_2$, MoSe$_2$, and WS$_2$ has a topologically trivial band structure, graphene on WSe$_2$ exhibits inverted bands. Using a realistic tight-binding model we find topologically protected helical edge states for graphene zigzag nanoribbons on WSe$_2$, demonstrating the quantum spin Hall effect. This model also features "half-topological states", which are protected against time-reversal disorder on one edge only.