Beugeling W, Kalesaki E, Delerue C, Niquet Y-M, Vanmaekelbergh D, Morais Smith C
Max-Planck-Institut für Physik komplexer Systeme, Nöthnitzer Straße 38, 01187 Dresden, Germany.
1] IEMN-Department ISEN, UMR CNRS 8520, 41 Boulevard Vauban, 59046 Lille, France [2] Physics and Materials Science Research Unit, University of Luxembourg, 162A Avenue de la Faïencerie, L-1511 Luxembourg, Luxembourg.
Nat Commun. 2015 Mar 10;6:6316. doi: 10.1038/ncomms7316.
Research on graphene has revealed remarkable phenomena arising in the honeycomb lattice. However, the quantum spin Hall effect predicted at the K point could not be observed in graphene and other honeycomb structures of light elements due to an insufficiently strong spin-orbit coupling. Here we show theoretically that 2D honeycomb lattices of HgTe can combine the effects of the honeycomb geometry and strong spin-orbit coupling. The conduction bands, experimentally accessible via doping, can be described by a tight-binding lattice model as in graphene, but including multi-orbital degrees of freedom and spin-orbit coupling. This results in very large topological gaps (up to 35 meV) and a flattened band detached from the others. Owing to this flat band and the sizable Coulomb interaction, honeycomb structures of HgTe constitute a promising platform for the observation of a fractional Chern insulator or a fractional quantum spin Hall phase.
对石墨烯的研究揭示了在蜂窝晶格中出现的显著现象。然而，由于自旋轨道耦合不够强，在石墨烯和其他轻元素的蜂窝结构中无法观测到在K点预测的量子自旋霍尔效应。在此我们从理论上表明，HgTe的二维蜂窝晶格可以结合蜂窝几何结构和强自旋轨道耦合的效应。通过掺杂实验可获取的导带，可以用类似于石墨烯的紧束缚晶格模型来描述，但要包括多轨道自由度和自旋轨道耦合。这导致了非常大的拓扑能隙（高达35 meV）以及一个与其他能带分离的平坦能带。由于这个平坦能带和可观的库仑相互作用，HgTe的蜂窝结构构成了一个用于观测分数量子霍尔绝缘体或分数量子自旋霍尔相的有前景的平台。
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