Stability conditions and phase diagrams for two-component Fermi gases with population imbalance

Journal Article · Fri Dec 15 04:00:00 EST 2006 · Physical Review. A

DOI:https://doi.org/10.1103/PHYSREVA.74.063603· OSTI ID:20976517

Qijin, Chen; Yan, He; Chien, C -C; Levin, K ^[1]

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1. James Franck Institute and Department of Physics, University of Chicago, Chicago, Illinois 60637 (United States)

Superfluidity in atomic Fermi gases with population imbalance has recently become an exciting research focus. There is considerable disagreement in the literature about the appropriate stability conditions for states in the phase diagram throughout the BCS to Bose-Einstein condensation crossover. Here we discuss these stability conditions for homogeneous polarized superfluid phases, and compare with recent alternative proposals. The requirement of a positive second-order partial derivative of the thermodynamic potential with respect to the fermionic excitation gap {delta} (at fixed chemical potentials) is demonstrated to be equivalent to the positive definiteness of the particle number susceptibility matrix. In addition, we show the positivity of the effective pair mass constitutes another nontrivial stability condition. These conditions determine the (local) stability of the system towards phase separation (or other ordered phases). We also study systematically the effects of finite temperature and the related pseudogap on the phase diagrams defined by our stability conditions.

• OSTI ID: 20976517
• Journal Information: Physical Review. A, Journal Name: Physical Review. A Journal Issue: 6 Vol. 74; ISSN 1050-2947; ISSN PLRAAN
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
BCS THEORY
BOSE-EINSTEIN CONDENSATION
EXCITATION
FERMI GAS
FERMIONS
FREE ENERGY
MATRICES
PHASE DIAGRAMS
POTENTIALS
STABILITY
SUPERFLUIDITY