A comprehensive study of bond bipolaron superconductivity in triangular lattice
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arXiv
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| Format: | Preprint |
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2025
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| _version_ | 1866913936137256960 |
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| author | Zhang, Chao |
| author_facet | Zhang, Chao |
| contents | We employ the diagrammatic Monte Carlo method with a lattice path-integral formulation for both electron and phonon degrees of freedom to investigate the formation and properties of bond polarons and bipolarons on a two-dimensional triangular lattice. In the adiabatic regime ($ω/t < 1.0$), single polarons remain light with a small effective mass, while bipolarons remain compact and lightweight, resulting in a high superfluid transition temperature $T_c$. We systematically study the dependence of $T_c$ on electron-phonon coupling strength and on-site interaction in the bond bipolaron model. Our results show that a moderate on-site repulsion enhances $T_c$ by stabilizing compact yet lightweight bipolarons, leading to high-$T_c$ superconductivity in the dilute limit. Notably, the triangular lattice sustains relatively high $T_c$ across a wide range of phonon frequencies, outperforming square lattice geometry. This enhancement arises from the higher coordination number and the bond-centered nature of the electron-phonon coupling. These findings suggest that triangular lattice geometry offers a promising platform for realizing high-$T_c$ bipolaronic superconductivity. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2507_07662 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | A comprehensive study of bond bipolaron superconductivity in triangular lattice Zhang, Chao Superconductivity Strongly Correlated Electrons We employ the diagrammatic Monte Carlo method with a lattice path-integral formulation for both electron and phonon degrees of freedom to investigate the formation and properties of bond polarons and bipolarons on a two-dimensional triangular lattice. In the adiabatic regime ($ω/t < 1.0$), single polarons remain light with a small effective mass, while bipolarons remain compact and lightweight, resulting in a high superfluid transition temperature $T_c$. We systematically study the dependence of $T_c$ on electron-phonon coupling strength and on-site interaction in the bond bipolaron model. Our results show that a moderate on-site repulsion enhances $T_c$ by stabilizing compact yet lightweight bipolarons, leading to high-$T_c$ superconductivity in the dilute limit. Notably, the triangular lattice sustains relatively high $T_c$ across a wide range of phonon frequencies, outperforming square lattice geometry. This enhancement arises from the higher coordination number and the bond-centered nature of the electron-phonon coupling. These findings suggest that triangular lattice geometry offers a promising platform for realizing high-$T_c$ bipolaronic superconductivity. |
| title | A comprehensive study of bond bipolaron superconductivity in triangular lattice |
| topic | Superconductivity Strongly Correlated Electrons |
| url | https://arxiv.org/abs/2507.07662 |