BCS-BEC crossover in an asymmetric two-component Fermi gas

Abstract

We discuss the superfluid phase transition of a strongly interacting Fermi gas with unequal (asymmetric) chemical potentials in two pairing hyperfine states, and map out its phase diagram near the BCS-BEC crossover. Our approach includes the fluctuation contributions of {}``preformed Cooper pairs'' to the thermodynamic potential at finite temperature. We show that, below a critical difference in chemical potentials between species, a normal gas is unstable towards the formation of either a finite-momentum paired Fulde-Ferrell-Larkin-Ovchinnikov superconducting phase or a uniform superfluid, depending on the asymmetry and interaction strengths. We determine the value of critical chemical potential mismatch, and find good qualitative agreement with a recent measurement by Zwierlein \textit{et al.} {[}Science \textbf{311}, 492 (2006){]}.

7 pages + 3 figures; To appear in Europhysics Letters

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Cited by in corpus (10)

• BEC-BCS crossover, phase transitions and phase separation in polarized resonantly-paired superfluids
• Zero Temperature Thermodynamics of Asymmetric Fermi Gases at Unitarity
• Finite temperature phase diagram of a spin-polarized ultracold Fermi gas in a highly elongated harmonic trap
• Superfluidity at the BEC-BCS crossover in two-dimensional Fermi gases with population and mass imbalance
• Itinerant ferromagnetism in an atomic Fermi gas: Influence of population imbalance
• Mean field thermodynamics of a spin-polarized spherically trapped Fermi gas at unitarity
• Breakdown of the local density approximation in interacting systems of cold fermions in strongly anisotropic traps
• Evaluating the phase diagram of superconductors with asymmetric spin populations
• Trapped Resonant Fermions above Superfluid Transition Temperature
• Spin-polarized Fermi superfluids as Bose-Fermi mixtures