title: Topological states in multi-orbital HgTe honeycomb lattices.
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.
authors.affiliation: Max-Planck-Institut für Physik komplexer Systeme, Nöthnitzer Straße 38, 01187 Dresden, Germany.
authors.forename: W
authors.initials: W
authors.lastname: Beugeling
authors.affiliation: 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.
authors.forename: E
authors.initials: E
authors.lastname: Kalesaki
authors.affiliation: IEMN-Department ISEN, UMR CNRS 8520, 41 Boulevard Vauban, 59046 Lille, France.
authors.forename: C
authors.initials: C
authors.lastname: Delerue
authors.affiliation: 1] Université Grenoble Alpes, INAC-SP2M, L_Sim, 17 avenue des Martyrs, 38054 Grenoble, France [2] CEA, INAC-SP2M, L_Sim, 17 avenue des Martyrs, 38054 Grenoble, France.
authors.forename: Y-M
authors.initials: YM
authors.lastname: Niquet
authors.affiliation: Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 1, 3584 CC Utrecht, The Netherlands.
authors.forename: D
authors.initials: D
authors.lastname: Vanmaekelbergh
authors.affiliation: Institute for Theoretical Physics, Center for Extreme Matter and Emergent Phenomena, Utrecht University, Leuvenlaan 4, 3584 CE Utrecht, The Netherlands.
authors.forename: C
authors.initials: C
authors.lastname: Morais Smith