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| Format: | Preprint |
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2025
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| Online-Zugang: | https://arxiv.org/abs/2507.09316 |
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| _version_ | 1866915385936183296 |
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| author | Shen, Yedi You, Sanyi Qiao, Zhenhua Niu, Qian |
| author_facet | Shen, Yedi You, Sanyi Qiao, Zhenhua Niu, Qian |
| contents | Quantum anomalous Hall effect has been widely explored in both ferromagnetic and antiferromagnetic systems. Here, we propose an interaction-driven paramagnetic quantum anomalous Hall effect emerging in the Fermion-Hubbard model on a dice lattice with weak spin-orbit coupling. Based on exact diagonalization calculations, the time-reversal symmetry breaking in the ground state is evidenced by nonuniform loop currents between nearest-neighbor sites. The many-body ground state possesses a Chern number of $\mathcal{C}=2$ or $6$, and strong correlation effects in the half-filled flat bands lead to a well-defined first excitation gap and a clear insulating gap, ensuring the robustness against thermal fluctuations and external perturbations. The interplay between spin-orbit coupling and Hubbard interaction allows tunability of various magnetic ground states, generating a rich phase diagram with competing ferromagnetic, antiferromagnetic, and paramagnetic orders. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2507_09316 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Quantum Anomalous Hall Effect in Flat Bands with Paramagnetism Shen, Yedi You, Sanyi Qiao, Zhenhua Niu, Qian Strongly Correlated Electrons Quantum anomalous Hall effect has been widely explored in both ferromagnetic and antiferromagnetic systems. Here, we propose an interaction-driven paramagnetic quantum anomalous Hall effect emerging in the Fermion-Hubbard model on a dice lattice with weak spin-orbit coupling. Based on exact diagonalization calculations, the time-reversal symmetry breaking in the ground state is evidenced by nonuniform loop currents between nearest-neighbor sites. The many-body ground state possesses a Chern number of $\mathcal{C}=2$ or $6$, and strong correlation effects in the half-filled flat bands lead to a well-defined first excitation gap and a clear insulating gap, ensuring the robustness against thermal fluctuations and external perturbations. The interplay between spin-orbit coupling and Hubbard interaction allows tunability of various magnetic ground states, generating a rich phase diagram with competing ferromagnetic, antiferromagnetic, and paramagnetic orders. |
| title | Quantum Anomalous Hall Effect in Flat Bands with Paramagnetism |
| topic | Strongly Correlated Electrons |
| url | https://arxiv.org/abs/2507.09316 |