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arXiv · 2009.00239

Interplay of local order and topology in the extended Haldane-Hubbard model

Can Shao·Eduardo V. Castro·Shijie Hu·Rubem Mondaini
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Abstract

We investigate the ground-state phase diagram of the spinful extended Haldane-Hubbard model on the honeycomb lattice using an exact-diagonalization, mean-field variational approach, and further complement it with the infinite density matrix renormalization group, applied to an infinite honeycomb cylinder. This model, governed by both on-site and nearest-neighbor interactions, can result in two types of insulators with finite local order parameters, either with spin or charge ordering. Moreover, a third one, a topologically nontrivial insulator with nonlocal order, is also manifest. We test expectations of previous analyses in spinless versions asserting that once a local order parameter is formed, the topological characteristics of the ground state, associated with a finite Chern number, are no longer present, resulting in a topologically trivial wave function. Our study confirms this overall picture, and highlights how finite-size effects may result in misleading conclusions on the coexistence of finite local order parameters and nontrivial topology in this model.

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Can Shao, Eduardo V. Castro, Shijie Hu, Rubem Mondaini. 2021-01-20. Interplay of local order and topology in the extended Haldane-Hubbard model. https://doi.org/10.1103/physrevb.103.035125

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