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Nature Research, Nature Communications, 1(6), 2015

DOI: 10.1038/ncomms7316

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Topological states in multi-orbital ​HgTe honeycomb lattices

Journal article published in 2015 by Wouter Beugeling, Efterpi Kalesaki, Christophe Delerue ORCID, Yann-Michel Niquet, Daniel Vanmaekelbergh, Cristiane de Morais Smith, C. Morais Smith
This paper is made freely available by the publisher.
This paper is made freely available by the publisher.

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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. ; Comment: includes supplementary material