(Invited) Topological States in Multi-Orbital Honeycomb Lattices of HgTe (CdTe) Quantum Dots
In the case of CdSe sheets , we predicted that their conduction band exhibits Dirac cones at two distinct energies and nontrivial flat bands. The lowest Dirac conduction band has s-orbital character and is equivalent to the π bands of graphene but with renormalized couplings. The conduction bands higher in energy have no counterpart in graphene; they combine a Dirac cone and flat bands because of their p-orbital character.
We also present very recent results on HgTe . We show theoretically that 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 quantum dots constitute a promising platform for the observation of a fractional Chern insulator or a fractional quantum spin Hall phase.
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