Pseudogap regime of a two-dimensional uniform Fermi gas

Abstract

We investigate pseudogap phenomena in a two-dimensional Fermi gas. Including pairing fluctuations within a self-consistent $T$-matrix approximation, we determine the pseudogap temperature $T^{\ast }$ below which a dip appears in the density of states $\rho (\omega )$ around the Fermi level. Evaluating $T^{\ast }$, we identify the pseudogap region in the phase diagram of this system. We find that, while the observed BKT (Berezinskii-Kosterlitz-Thouless) transition temperature $T_{\mathrm{BKT}}^{\exp }$ in a ${}^6$Li Fermi gas is in the pseudogap regime, the detailed pseudogap structure in $\rho (\omega )$ at $T_{\mathrm{BKT}}^{\exp }$ still differs from a fully-gapped one, indicating the importance of amplitude fluctuations in the Cooper channel there. Since the observed $T_{\mathrm{BKT}}^{\exp }$ in the weak-coupling regime cannot be explained by the recent BKT theory which only includes phase fluctuations, our results may provide a hint about how to improve this BKT theory. Although $\rho (\omega )$ has not been measured in this system, we show that the assessment of our results is still possible by using the observable Tan's contact.

23 pages, 9 figures

References in corpus (23)

• Many-Body Physics with Ultracold Gases
• Theory of ultracold Fermi gases
• Scanning tunneling spectroscopy of high-temperature superconductors
• Collective excitations of a degenerate gas at the BEC-BCS crossover
• Using photoemission spectroscopy to probe a strongly interacting Fermi gas
• Resonantly-paired fermionic superfluids
• Thermodynamics of the BCS-BEC crossover
• Observation of pseudogap behavior in a strongly interacting Fermi gas
• Radiofrequency spectroscopy of a strongly interacting two-dimensional Fermi gas
• Observation of a two-dimensional Fermi gas of atoms
• Observation of the Berezinskii-Kosterlitz-Thouless Phase Transition in an Ultracold Fermi Gas
• Observation of pair condensation in the quasi-2D BEC-BCS crossover
• Evolution of the Normal State of a Strongly Interacting Fermi Gas from a Pseudogap Phase to a Molecular Bose Gas
• Breakdown of Fermi liquid description for strongly interacting fermions
• Pseudo-gap pairing in ultracold Fermi atoms
• Enhanced paraconductivity-like fluctuations in the radio frequency spectra of ultracold Fermi atoms
• Cooper pairing above the critical temperature in a unitary Fermi gas
• The effect of population imbalance on the Berezinskii-Kosterlitz-Thouless phase transition in a superfluid Fermi gas
• Pairing effects in the normal phase of a two-dimensional Fermi gas
• A two-dimensional Fermi liquid with attractive interactions
• Pairing and radio-frequency spectroscopy in two-dimensional Fermi gases
• Quantum fluctuations and vortex-antivortex unbinding in the 2D BCS-BEC crossover
• Pseudogap phenomena near the BKT transition of a two-dimensional ultracold Fermi gas in the crossover region

Cited by in corpus (1)

• Low-Dimensional Fluctuations and Pseudogap in Gaudin-Yang Fermi Gases