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arXiv · 2212.10835

Higher-order topological insulator in a modified Haldane-Hubbard model

Tian-Cheng Yi·Hai-Qing Lin·Rubem Mondaini
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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 non-interacting 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 non-trivial topological bulk coexists with an interaction-driven charge-density-wave, whose emergence is characterized by a $Z_2$-symmetry breaking within the 3$d$-Ising universality class.

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Tian-Cheng Yi, Hai-Qing Lin, Rubem Mondaini. 2022-12-21. Higher-order topological insulator in a modified Haldane-Hubbard model. https://doi.org/10.1103/physrevb.107.165135

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