Superfluid density of states and pseudogap phenomenon in the BCS-BEC crossover regime of a superfluid Fermi gas

Abstract

We investigate single-particle excitations and strong-coupling effects in the BCS-BEC crossover regime of a superfluid Fermi gas. Including phase and amplitude fluctuations of the superfluid order parameter within a $T$-matrix theory, we calculate the superfluid density of states (DOS), as well as single-particle spectral weight, over the entire BCS-BEC crossover region below the superfluid transition temperature $T_{\mathrm{c}}$. We clarify how the pseudogap in the normal state evolves into the superfluid gap, as one passes through $T_{\mathrm{c}}$. While the pseudogap in DOS continuously evolves into the superfluid gap in the weak-coupling BCS regime, the superfluid gap in the crossover region is shown to appear in DOS after the pseudogap disappears below $T_{\mathrm{c}}$. In the phase diagram with respect to the temperature and interaction strength, we determine the region where strong pairing fluctuations dominate over single-particle properties of the system. Our results would be useful for the study of strong-coupling phenomena in the BCS-BEC crossover regime of a superfluid Fermi gas.

22 pages, 8 figures

References in corpus (10)

• 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
• Observation of pseudogap behavior in a strongly interacting Fermi gas
• BCS-BEC crossover at finite temperature in the broken-symmetry phase
• Pseudo-gap pairing in ultracold Fermi atoms
• Photoemission spectrum and effect of inhomogeneous pairing fluctuations in the BCS-BEC crossover regime of an ultracold Fermi gas
• Superconducting Fluctuation and Pseudogap in Disordered Short Coherence Length Superconductor

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• Pseudogap phenomena in ultracold atomic Fermi gases
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• Hartree shift in unitary Fermi gases
• Excitation properties and effects of mass imbalance in the BCS-BEC crossover regime of an ultracold Fermi gas
• Mesoscopic spin transport between strongly interacting Fermi gases
• Strong-coupling corrections to spin susceptibility in the BCS-BEC crossover regime of a superfluid Fermi gas
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• Hidden fermionic excitation in the superconductivity of the strongly attractive Hubbard model
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• Momentum-resolved spectroscopy of a Fermi liquid
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• Inhomogeneous Pseudogap Phenomenon in the BCS-BEC Crossover Regime of a Trapped Superfluid Fermi Gas
• Strong coupling effects on specific heat in the BCS-BEC crossover
• Theory of Photoemission-type Experiment in the BCS-BEC Crossover Regime of a Superfluid Fermi Gas