Suppression of topological Mott-Hubbard phases by multiple charge orders in the honeycomb extended Hubbard model
written by: Mario Bijelic, Ryui Kaneko, Claudius Gros, Roser Valentí
We investigate the competition between charge-density-wave (CDW) states and a Coulomb interaction-driven topological Mott insulator (TMI) in the honeycomb extended Hubbard model. For the spinful model with onsite (U) and next-nearest-neighbor (V2) Coulomb interactions at half filling we find two peculiar six-sublattice charge-density-wave (CDW) insulating states by using variational Monte Carlo simulation as well as the Hartree-Fock approximation. We observe that conventional ordered states always win with respect to the TMI. The ground state is given in the large-V2 region by a CDW characterized by a 220200 (001122) charge configuration for smaller (larger) U, where 0, 1 and 2 denote essentially empty, singly- and doubly-occupied sites. Within the 001122-type CDW phase, we find a magnetic transition driven by an emergent coupled-dimer antiferromagnet on an effective square lattice of singly-occupied sites. Possible realizations of the states found are discussed.
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The final paper can be found at Phys. Rev B 97, 125142 (2018)