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arXiv · 1503.06066

Topological states in multi-orbital HgTe honeycomb lattices

W. Beugeling·E. Kalesaki·C. Delerue·Y. -M. Niquet·D. Vanmaekelbergh·C. Morais Smith
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Abstract

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.

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W. Beugeling, E. Kalesaki, C. Delerue, Y. -M. Niquet, D. Vanmaekelbergh, C. Morais Smith. 2015-03-20. Topological states in multi-orbital HgTe honeycomb lattices. https://doi.org/10.1038/ncomms7316

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