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.

arXiv comment23 pages, 9 figures

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Cited by in corpus (3)

• Role of the confinement-induced effective range on the thermodynamics of a strongly correlated Fermi gas in two dimensions
• Low-Dimensional Fluctuations and Pseudogap in Gaudin-Yang Fermi Gases
• Dimensionality-induced BCS-BEC crossover in layered superconductors