Mixtures of ultracold fermions with unequal masses

Abstract

We analyze the phase diagram of superfluidity for two-species fermion mixtures from the Bardeen-Cooper-Schrieffer (BCS) to Bose-Einstein condensation (BEC) limit as a function of scattering parameter, population imbalance and mass anisotropy. We identify regions corresponding to normal, or uniform/non-uniform superfluid phases, and discuss topological quantum phase transitions in the BCS, unitarity and BEC limits. We derive the Ginzburg-Landau equation near the critical temperature, and show that it describes a dilute mixture of paired and unpaired fermions in the BEC limit. We also obtain the zero temperature low frequency and long wavelength collective excitation spectrum, and recover the Bogoliubov relation for weakly interacting dilute bosons in the BEC limit. Lastly, we discuss the effects of harmonic traps and the resulting density profiles in the BEC regime.

14 pages, 9 figures. Extended version of cond-mat/0606624

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Cited by in corpus (15)

• Theory of ultracold Fermi gases
• Ultra-cold Polarized Fermi Gases
• Energetics and Structural Properties of Trapped Two-Component Fermi Gases
• Superfluid pairing between fermions with unequal masses
• Fermi-Fermi Mixtures in the Strong Attraction Limit
• Hartree-Fock-Bogoliubov Theory of Polarized Fermi Systems
• Experimental conditions for observation of electron-hole superfluidity in GaAs heterostructures
• Chandrasekhar-Clogston limit and phase separation in Fermi mixtures at Unitarity
• Quantum phases of Fermi-Fermi mixtures in optical lattices
• Hetero pairing and component-dependent pseudogap phenomena in an ultracold Fermi gas with mass imbalance
• Quantum Lifshitz points and fluctuation-induced first-order phase transitions in imbalanced Fermi mixtures
• Temperature Effects in a Fermi Gas with Population Imbalance
• Vortex core states in superfluid Fermi-Fermi mixtures with unequal masses
• Collective excitation and stability of flow-induced gapless Fermi superfluids
• Damping of the Anderson-Bogolyubov mode by spin and mass imbalance in Fermi mixtures