Properties of a Fermi liquid at the superfluid transition in the crossover region between BCS superconductivity and Bose-Einstein condensation

Haussmann, Rudolf

doi:10.1103/physrevb.49.12975

Cited by 254 publications

(350 citation statements)

References 7 publications

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“…• double-dot-dashed line: BCS mean eld theory • open circles: Diagrammatic Monte Carlo calculations [113] • open squares: Quantum Monte Carlo calculations [136] • dotted line: GG perturbation theory [137,138] • dashed line: GG 0 perturbation theory [139] • triple-dot-dashed line: Ladder diagrams approximation [140] • dot-dashed line: Pseudogap theory [139] • solid line: Gaussian pair uctuation/Nozières-Schmitt Rink theory [141] Our data clearly discriminates between these theories. We observe that none of them account for our data over their full range.…”

Section: Direct Comparison With Theorymentioning

confidence: 99%

Thermodynamics of Ultracold Fermi Gases

Nascimbène

Navon

Chevy

et al. 2010

Latin America Optics and Photonics Conference

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Section: Direct Comparison With Theorymentioning

confidence: 99%

Thermodynamics of Ultracold Fermi Gases

Nascimbène

Navon

Chevy

et al. 2010

Latin America Optics and Photonics Conference

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“…The theory is based on a conserving, so-called Φ-derivable approach to the many-body problem, in which the exact one-or two-particle Green functions serve as an infinite set of variational parameters. It is an extension of earlier work by one of us [29,30,31] and employs a combination of the Luttinger-Ward and DeDominicis-Martin approach for obtaining the grand canonical potential and the entropy, respectively. The condition of gaplessness is enforced by a modified coupling constant, thus accounting for the proper low energy behaviour in terms of a Bogoliubov-Anderson mode.…”

Section: Introductionmentioning

confidence: 99%

Thermodynamics of the BCS-BEC crossover

et al. 2007

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We present a self-consistent theory for the thermodynamics of the BCS-BEC crossover in the normal and superfluid phase which is both conserving and gapless. It is based on the variational many-body formalism developed by Luttinger and Ward and by DeDominicis and Martin. Truncating the exact functional for the entropy to that obtained within a ladder approximation, the resulting self-consistent integral equations for the normal and anomalous Green functions are solved numerically for arbitrary coupling. The critical temperature, the equation of state and the entropy are determined as a function of the dimensionless parameter 1/kF a, which controls the crossover from the BCS-regime of extended pairs to the BEC-regime of tightly bound molecules. The tightly bound pairs turn out to be described by a Popov-type approximation for a dilute, repulsive Bose gas. Even though our approximation does not capture the critical behaviour near the continuous superfluid transition, our results provide a consistent picture for the complete crossover thermodynamics which compare well with recent numerical and field-theoretic approaches at the unitarity point.

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“…The NSR theory has been investigated by many authors because the gap in the fermionic excitations is considered to be the pseudogap. 20,24,25,26,27) The existence of the pre-formed pairs has been proposed phenomenologically by Geshkenbein et al 28) with reference to the sign problem of the fluctuational Hall effect. 46) The strength of the superconducting coupling is indicated by the ratio T MF c /ε F .…”

Section: §1 Introductionmentioning

confidence: 99%

“…19,22,23,24,25,26,27,28,29,30,31,32,33,34,3 They are classified into some kinds. The scenario based on the phase fluctuations has been proposed by Emery and Kivelson 21) and calculated by other authors.…”

Section: §1 Introductionmentioning

confidence: 99%

Pseudogap Phenomena and Superconducting Fluctuations in Hubbard Model for High-T_cCuprates

2001

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The pseudogap phenomena in High-Tc cuprates are investigated on the basis of the Hubbard model which includes only the on-site repulsive interaction U . We consider the pairing scenario for the pseudogap. The pseudogap arises from the resonance scattering due to the strong superconducting fluctuations. First, the electronic state and the anti-ferromagnetic spin fluctuations are calculated by using the fluctuation exchange (FLEX) approximation. The T-matrix which is the propagator of the superconducting fluctuations is calculated by extending theÉliashberg equation. The characteristics of the superconducting fluctuations due to the pairing interaction arising from the spin fluctuations are represented in the T-matrix. The self-energy due to the superconducting fluctuations is calculated by the T-matrix approximation. The pseudogap is shown in the single particle properties and the magnetic properties. Moreover, a comprehensive explanation of the doping dependence of the pseudogap is obtained. Furthermore, we apply the theory to the electron-doped cuprates and obtain the consistent results with the recent experiments. Finally, the self-consistent calculation for the spin fluctuations, superconducting fluctuations and the single particle properties are carried out within the FLEX and the self-consistent T-matrix approximations. The relation between the superconducting fluctuations and the spin fluctuations are clarified. The calculated superconducting critical temperature Tc is remarkably reduced from the results of the mean field (FLEX) calculation. In particular, it is shown that the critical temperature decreases with decreasing doping in the under-doped region with large U . The pseudogap phenomena in under-doped High-T c cuprates have been interested for many years. The pseudogap is considered to be a key issue for the comprehensive understanding of the High-T c superconductivity.The pseudogap phenomena mean the suppression of the spectral weight above T c without any long range order. They are universal phenomena observed in various compounds of High-T c cuprates in the under-doped region. First, the pseudogap was found in the magnetic excitation channel by the nuclear magnetic resonance (NMR) experiment. 1) At present, the pseudogap phenomena have been observed in various quantities which include NMR, 1, 2, 3, 4, 5, 6, 7) neutron scattering, 8) transport, 9, 10) optical spectrum, 11) electronic specific heat, 12) density of states 13) and the single particle spectral weight. 14) The experimental results are reviewed in ref. 15.There are many theoretical scenarios proposed for the pseudogap phenomena. An important one is the resonating valence bond (RVB) theory. The RVB theory is an approach from the non-Fermi liquid state and attributes the pseudogap to the singlet pairing of the spinons. 16) As an approach from the Fermi liquid state, the magnetic * E-mail: yanase@hosi.phys.s.u-tokyo.ac.jp * * Present address: Department of Physics, University of Tokyo, Tokyo 113-0033 scenario has been investigated. 17,18) ...

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Properties of a Fermi liquid at the superfluid transition in the crossover region between BCS superconductivity and Bose-Einstein condensation

Cited by 254 publications

References 7 publications

Thermodynamics of Ultracold Fermi Gases

Thermodynamics of Ultracold Fermi Gases

Thermodynamics of the BCS-BEC crossover

Pseudogap Phenomena and Superconducting Fluctuations in Hubbard Model for High-T_cCuprates

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Properties of a Fermi liquid at the superfluid transition in the crossover region between BCS superconductivity and Bose-Einstein condensation

Cited by 254 publications

References 7 publications

Thermodynamics of Ultracold Fermi Gases

Thermodynamics of Ultracold Fermi Gases

Thermodynamics of the BCS-BEC crossover

Pseudogap Phenomena and Superconducting Fluctuations in Hubbard Model for High-TcCuprates

Contact Info

Product

Resources

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Pseudogap Phenomena and Superconducting Fluctuations in Hubbard Model for High-T_cCuprates