BCS-BEC crossover in atomic Fermi gases in quasi-two-dimensional Lieb lattices: Effects of flat band and finite temperature
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| Main Authors: | , , , , , |
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| Format: | Preprint |
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2024
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| _version_ | 1866916081774362624 |
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| author | Deng, Hao Sun, Lin Li, Chuping Wu, Yuxuan Wu, Junru Chen, Qijin |
| author_facet | Deng, Hao Sun, Lin Li, Chuping Wu, Yuxuan Wu, Junru Chen, Qijin |
| contents | We investigate the finite-temperature superfluid behavior of ultracold atomic Fermi gases in quasi-two-dimensional Lieb lattices with a short-range attractive interaction, using a pairing fluctuation theory within the BCS-BEC crossover framework. We find that the presence of a flat band, along with van Hove singularities, leads to exotic quantum phenomena. As the Fermi level enters the flat band, both the gap and the superfluid transition temperature $T_c$ as a function of interaction change from a conventional exponential behavior into an unusual power law, and the evolution of superfluid densities with temperature also follows a power law even at weak interactions. The quantum geometric effects, manifested by an enhanced effective pair hopping integral, may contribute significantly to both $T_c$ and the superfluidities. As the chemical potential crosses the van Hove singularities in the weak interaction regime, the nature of pairing changes between particle-like and hole-like. A pair density wave state emerges at high densities with a relatively strong interaction strength. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2401_02990 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | BCS-BEC crossover in atomic Fermi gases in quasi-two-dimensional Lieb lattices: Effects of flat band and finite temperature Deng, Hao Sun, Lin Li, Chuping Wu, Yuxuan Wu, Junru Chen, Qijin Quantum Gases We investigate the finite-temperature superfluid behavior of ultracold atomic Fermi gases in quasi-two-dimensional Lieb lattices with a short-range attractive interaction, using a pairing fluctuation theory within the BCS-BEC crossover framework. We find that the presence of a flat band, along with van Hove singularities, leads to exotic quantum phenomena. As the Fermi level enters the flat band, both the gap and the superfluid transition temperature $T_c$ as a function of interaction change from a conventional exponential behavior into an unusual power law, and the evolution of superfluid densities with temperature also follows a power law even at weak interactions. The quantum geometric effects, manifested by an enhanced effective pair hopping integral, may contribute significantly to both $T_c$ and the superfluidities. As the chemical potential crosses the van Hove singularities in the weak interaction regime, the nature of pairing changes between particle-like and hole-like. A pair density wave state emerges at high densities with a relatively strong interaction strength. |
| title | BCS-BEC crossover in atomic Fermi gases in quasi-two-dimensional Lieb lattices: Effects of flat band and finite temperature |
| topic | Quantum Gases |
| url | https://arxiv.org/abs/2401.02990 |