Thermal transitions, pseudogap behavior and BCS-BEC crossover in Fermi-Fermi mixtures

Abstract

We study the mass imbalanced Fermi-Fermi mixture within the framework of a two-dimensional lattice fermion model. Based on the thermodynamic and species dependent quasiparticle behavior we map out the finite temperature phase diagram of this system and show that unlike the balanced Fermi superfluid there are now two different pseudogap regimes as PG-I and PG-II. While within the PG-I regime both the fermionic species are pseudogapped, PG-II corresponds to the regime where pseudogap feature survives only in the light species. We believe that the single particle spectral features that we discuss in this paper are observable through the species resolved radio frequency spectroscopy and momentum resolved photo emission spectroscopy measurements on systems such as, 6${}_{Li}$-40${}_K$ mixture. We further investigate the interplay between the population and mass imbalances and report that at a fixed population imbalance the BCS-BEC crossover in a Fermi-Fermi mixture would require a critical interaction (U${}_c$), for the realization of the uniform superfluid state. The effect of imbalance in mass on the exotic Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) superfluid phase has been probed in detail in terms of the thermodynamic and quasiparticle behavior of this phase. It has been observed that in spite of the s-wave symmetry of the pairing field a nodal superfluid gap is realized in the LO regime. Our results on the various thermal scales and regimes are expected to serve as benchmarks for the experimental observations on 6${}_{Li}$-40${}_K$ mixture.

20 pages, 22 figures, minor typo corrections and replacement of a figure

References in corpus (38)

• Spin-Injection Spectroscopy of a Spin-Orbit Coupled Fermi Gas
• Collective excitations of a degenerate gas at the BEC-BCS crossover
• Quantum degenerate dipolar Fermi gas
• Observation of Phase Separation in a Strongly-Interacting Imbalanced Fermi Gas
• Nature of the superconductor-insulator transition in disordered superconductors
• Thermodynamics of the BCS-BEC crossover
• Phase diagram of a two-component Fermi gas with resonant interactions
• Observation of pseudogap behavior in a strongly interacting Fermi gas
• Exploring an ultracold Fermi-Fermi mixture: Interspecies Feshbach resonances and scattering properties of 6Li and 40K
• Deformation of a Trapped Fermi Gas with Unequal Spin Populations
• Critical Temperature and Thermodynamics of Attractive Fermions at Unitarity
• Quantum degenerate two-species Fermi-Fermi mixture coexisting with a Bose-Einstein condensate
• BEC-BCS crossover, phase transitions and phase separation in polarized resonantly-paired superfluids
• Pairing without Superfluidity: The Ground State of an Imbalanced Fermi Mixture
• Observation of pair condensation in the quasi-2D BEC-BCS crossover
• Ultracold Heteronuclear Fermi-Fermi Molecules
• Two-species fermion mixtures with population imbalance
• Fermion Superfluids of Non-Zero Orbital Angular Momentum near Resonance
• Finite temperature phase diagram of a polarized Fermi gas in an optical lattice
• Polarized Fermi condensates with unequal masses: Tuning the tricritical point
• Strongly-resonant p-wave superfluids
• Thermodynamics of a Trapped Unitary Fermi Gas
• Pairing and Superfluid Properties of Dilute Fermion Gases at Unitarity
• Heavy-Light Fermion Mixtures at Unitarity
• All-optical production of a degenerate mixture of 6Li and 40K and creation of heteronuclear molecules
• Resonant pairing between Fermions with unequal masses
• Mixtures of ultracold fermions with unequal masses
• Phase structure of mass- and spin-imbalanced unitary Fermi gases
• Superfluid shells for trapped fermions with mass and population imbalance
• Pair formation and collapse in imbalanced Fermion populations with unequal masses
• Asymmetric Fermi superfluid with different atomic species in a harmonic trap
• Berezinskii-Kosterlitz-Thouless transition and BCS-Bose crossover in the two-dimensional attractive Hubbard model
• Low temperature properties of the fermionic mixtures with mass imbalance in optical lattice
• Population imbalanced lattice fermions near the BCS-BEC crossover: I.The breached pair and metastable FFLO phases
• Population imbalanced lattice fermions near the BCS-BEC crossover: II. The FFLO regime and its thermal signatures
• Pairing-gap, pseudo-gap, and no-gap phases in the radio-frequency spectra of a trapped unitary 6Li gas
• Hetero pairing and component-dependent pseudogap phenomena in an ultracold Fermi gas with mass imbalance
• Anomalous pseudogap in population imbalanced Fermi superfluids

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