Spin-polarized Fermi superfluids as Bose-Fermi mixtures

Journal Article · Wed Aug 15 04:00:00 EDT 2007 · Physical Review. A

DOI:https://doi.org/10.1103/PHYSREVA.76.023614· OSTI ID:21016022

Taylor, E; Griffin, A; Ohashi, Y ^[1]

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1. Department of Physics, University of Toronto, Toronto, Ontario, M5S 1A7 (Canada)

In the strong-coupling Bose-Einstein condensation (BEC) region where a Feshbach resonance gives rise to tightly bound dimer molecules, we show that a spin-polarized Fermi superfluid reduces to a simple Bose-Fermi mixture of Bose-condensed dimers and the leftover unpaired fermions. Using a many-body functional integral formalism, the Gaussian fluctuations give rise to an induced dimer-dimer interaction mediated by the unpaired fermions, with the dimer-fermion vertex being given by the (mean-field) Born approximation. Treating the pairing fluctuations to quartic order, we show how the action for a spin-polarized Fermi superfluid reduces to one for a Bose-Fermi mixture. This Bose-Fermi action includes an expression for the effective dimer-unpaired fermion interaction in a spin-polarized Fermi superfluid beyond the Born approximation, in the BEC limit. In the low-density limit, we show how this dimer-fermion interaction gives the s-wave scattering length a{sub BF}=1.18a{sub F} (a{sub F} is the s-wave fermion scattering length), a result first derived by Skorniakov and Ter-Martirosian in 1957 for three interacting fermions.

• OSTI ID: 21016022
• Journal Information: Physical Review. A, Journal Name: Physical Review. A Journal Issue: 2 Vol. 76; ISSN 1050-2947; ISSN PLRAAN
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
BINARY MIXTURES
BORN APPROXIMATION
BOSE-EINSTEIN CONDENSATION
BOSONS
DENSITY
DIMERS
FERMIONS
FLUCTUATIONS
INTEGRALS
INTERACTIONS
MANY-BODY PROBLEM
MEAN-FIELD THEORY
MOLECULES
RESONANCE
S WAVES
SCATTERING LENGTHS
SPIN ORIENTATION
STRONG-COUPLING MODEL
SUPERFLUIDITY