Pseudogap temperature and effects of a harmonic trap in the BCS-BEC crossover regime of an ultracold Fermi gas

Abstract

We theoretically investigate excitation properties in the pseudogap regime of a trapped Fermi gas. Using a combined $T$-matrix theory with the local density approximation, we calculate strong-coupling corrections to single-particle local density of states (LDOS), as well as the single-particle local spectral weight (LSW). Starting from the superfluid phase transition temperature $T_{\mathrm{c}}$, we clarify how the pseudogap structures in these quantities disappear with increasing the temperature. As in the case of a uniform Fermi gas, LDOS and LSW give different pseudogap temperatures $T^{\ast }$ and $T^{\ast \ast }$ at which the pseudogap structures in these quantities completely disappear. Determining $T^{\ast }$ and $T^{\ast \ast }$ over the entire BCS (Bardeen-Cooper-Schrieffer)-BEC (Bose-Einstein condensate) crossover region, we identify the pseudogap regime in the phase diagram with respect to the temperature and the interaction strength. We also show that the so-called back-bending peak recently observed in the photoemission spectra by JILA group may be explained as an effect of pseudogap phenomenon in the trap center. Since strong pairing fluctuations, spatial inhomogeneity, and finite temperatures, are important keys in considering real cold Fermi gases, our results would be useful for clarifying normal state properties of this strongly interacting Fermi system.

25 pages, 12 figures

References in corpus (14)

• Many-Body Physics with Ultracold Gases
• Theory of ultracold Fermi gases
• Scanning tunneling spectroscopy of high-temperature superconductors
• Collective excitations of a degenerate gas at the BEC-BCS crossover
• Using photoemission spectroscopy to probe a strongly interacting Fermi gas
• Generalized Virial Theorem and Pressure Relation for a strongly correlated Fermi gas
• Observation of pseudogap behavior in a strongly interacting Fermi gas
• Verification of universal relations in a strongly interacting Fermi gas
• Evolution of the Normal State of a Strongly Interacting Fermi Gas from a Pseudogap Phase to a Molecular Bose Gas
• Pseudo-gap pairing in ultracold Fermi atoms
• Onset of a Pseudogap Regime in Ultracold Fermi Gases
• Superfluid density of states and pseudogap phenomenon in the BCS-BEC crossover regime of a superfluid Fermi gas
• Photoemission spectrum and effect of inhomogeneous pairing fluctuations in the BCS-BEC crossover regime of an ultracold Fermi gas
• Evolution of the Pseudogap in a polarized Fermi gas

Cited by in corpus (27)

• The BCS-BEC crossover: From ultra-cold Fermi gases to nuclear systems
• Momentum-dependent pseudogaps in the half-filled two-dimensional Hubbard model
• Spin susceptibility and fluctuation corrections in the BCS-BEC crossover regime of an ultracold Fermi gas
• Uniform spin susceptibility and spin-gap phenomenon in the BCS-BEC crossover regime of an ultracold Fermi gas
• Low-dimensional pairing fluctuations and pseudogapped photoemission spectrum in a trapped two-dimensional Fermi gas
• Specific heat and effects of pairing fluctuations in the BCS-BEC crossover regime of an ultracold Fermi gas
• Mesoscopic spin transport between strongly interacting Fermi gases
• Strong-coupling corrections to spin susceptibility in the BCS-BEC crossover regime of a superfluid Fermi gas
• Local Photoemission Spectra and Effects of Spatial Inhomogeneity in the BCS-BEC Crossover Regime of a Trapped Ultracold Fermi Gas
• Pair condensation in a Finite Trapped Fermi Gas
• Pseudogap phenomenon and effects of population imbalance in the normal state of a unitary Fermi gas
• Precursor of Superfluidity in a Strongly Interacting Fermi Gas with Negative Effective Range
• Coexistence of superfluid gap and pseudogap in the BCS-BEC crossover regime of a trapped Fermi gas below $T_{\mathrm{c}}$
• Pairing fluctuations and anisotropic pseudogap phenomenon in an ultracold superfluid Fermi gas with plural $p$-wave superfluid phases
• Single-Particle properties of a strongly-interacting Bose-Fermi mixture with mass and population imbalance
• Strong-Coupling and Finite Temperature Effects on $p$-wave Contacts
• Quasiparticle Dispersions and Lifetimes in the Normal State of the BCS-BEC Crossover
• Spin susceptibility and effects of a harmonic trap in the BCS-BEC crossover regime of an ultracold Fermi gas
• Single-particle Excitations and Effects of Hetero-pairing Fluctuations in a Bose-Fermi Mixture with a Feshbach Resonance
• Isothermal compressibility and effects of multi-body molecular interactions in a strongly interacting ultracold Fermi gas
• Spin-dipole mode in a trapped Fermi gas near unitarity
• Two-dimensional pseudogap effects of an ultracold Fermi gas in the BCS-BEC crossover region
• Specific Heat and Effects of Uniaxial Anisotropy of a $p$-wave Pairing Interaction in a Strongly Interacting Ultracold Fermi Gas
• Triplet pair amplitude in a trapped $s$-wave superfluid Fermi gas with broken spin rotation symmetry. II. Three dimensional continuum case
• Spin Susceptibility and Strong Coupling Effects in an Ultracold Fermi Gas
• Spin susceptibility and effects of inhomogeneous strong pairing fluctuations in a trapped ultracold Fermi gas
• Strong coupling effects on specific heat in the BCS-BEC crossover