arXiv:2212.10835 · Physical review. B./Physical review. B
Higher-order topological insulator in a modified Haldane-Hubbard model
Tian-Cheng Yi, Hai‐Qing Lin, Rubem Mondaini
Abstract
We investigate the ground-state phase diagram of a modified spinless Haldane-Hubbard model, with broken threefold rotational symmetry, employing exact diagonalization calculations. The interplay of asymmetry, interactions, and topology gives rise to a rich phase diagram. The noninteracting limit of the Hamiltonian exhibits a higher-order topological insulator characterized by the existence of corner modes, in contrast to known chiral edge metallic states of the standard Haldane model. Our investigation demonstrates that these symmetry-protected states are robust to the presence of finite interactions. Furthermore, in certain regimes of parameters, we show that a topological Mott insulator exists in this model, where a nontrivial topological bulk coexists with an interaction-driven charge-density wave, whose emergence is characterized by a ${Z}_{2}$-symmetry breaking within the $3d\text{-Ising}$ universality class.