Interaction-Driven Intervalley Coherence with Emergent Kekulé Orbitons
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arXiv
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| Format: | Preprint |
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2025
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| _version_ | 1866913820216131584 |
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| author | Chen, Hua |
| author_facet | Chen, Hua |
| contents | The $p$-orbital doublet in a honeycomb lattice is concretely studied with interacting spinless fermions at half filling. The Dirac fermions with linear dispersion at $\pm K$ valleys govern the non-interacting low-energy physics. In the weak-coupling regime, the Dirac fermions are gaped due to the spontaneous generation of mass terms through a uniform axial orbital ordering, rendering the system into the quantum anomalous Hall insulator phase with a nonzero Chern number. Surprisingly, the intermediate many-particle interaction produces the intervalley coherence between $\pm K$ valleys by developing complex polar orbital orderings in a tripled Wigner-Seitz cell. This phase is shown to have a deep connection with the low-energy physical behavior described by the orbital exchange model in the Mott insulating phase. The classical ground-state manifold in the Mott regime enjoys a continuous symmetry characterized by the intervalley coherent phase. Finally, the quantum fluctuation selects a unique ground state with emergent Kekulé orbitons through the order-by-disorder mechanism. Our findings provide insights for a direction of searching for Kekulé distortion in correlated multi-orbital systems. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2505_02461 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Interaction-Driven Intervalley Coherence with Emergent Kekulé Orbitons Chen, Hua Strongly Correlated Electrons Quantum Physics The $p$-orbital doublet in a honeycomb lattice is concretely studied with interacting spinless fermions at half filling. The Dirac fermions with linear dispersion at $\pm K$ valleys govern the non-interacting low-energy physics. In the weak-coupling regime, the Dirac fermions are gaped due to the spontaneous generation of mass terms through a uniform axial orbital ordering, rendering the system into the quantum anomalous Hall insulator phase with a nonzero Chern number. Surprisingly, the intermediate many-particle interaction produces the intervalley coherence between $\pm K$ valleys by developing complex polar orbital orderings in a tripled Wigner-Seitz cell. This phase is shown to have a deep connection with the low-energy physical behavior described by the orbital exchange model in the Mott insulating phase. The classical ground-state manifold in the Mott regime enjoys a continuous symmetry characterized by the intervalley coherent phase. Finally, the quantum fluctuation selects a unique ground state with emergent Kekulé orbitons through the order-by-disorder mechanism. Our findings provide insights for a direction of searching for Kekulé distortion in correlated multi-orbital systems. |
| title | Interaction-Driven Intervalley Coherence with Emergent Kekulé Orbitons |
| topic | Strongly Correlated Electrons Quantum Physics |
| url | https://arxiv.org/abs/2505.02461 |