Using dynamical mean-field theory and exact diagonalization we study the phase diagram of the repulsive Haldane-Hubbard model, varying the interaction strength and the sublattice potential difference. In addition to the quantum Hall phase with Chern number C=2 and the band insulator with C=0 present already in the noninteracting model, the system also exhibits a C=0 Mott insulating phase, and a C=1 quantum Hall phase. We explain the latter phase by a spontaneous symmetry breaking where one of the spin-components is in the Hall state and the other in the band insulating state.
@article{arxiv.1512.08804,
title = {Topological phase transitions in the repulsively interacting Haldane-Hubbard model},
author = {Tuomas I. Vanhala and Topi Siro and Long Liang and Matthias Troyer and Ari Harju and Päivi Törmä},
journal= {arXiv preprint arXiv:1512.08804},
year = {2016}
}