Current-current Fermi-liquid corrections to the superconducting fluctuations on conductivity and diamagnetism

Fanfarillo, Laura; Castellani, C.

doi:10.1103/physrevb.85.024507

Cited by 11 publications

(15 citation statements)

References 22 publications

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“…The evolution of the static properties of a superconductor between BCS and BEC regimes has been extensively discussed in the condensed matter context [4,5,[7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]42] and also for optical lattices of ultracold atoms [24,25]. The BCS-BEC crossover is determined by the interplay between 0 E and F E : the system is deep in the BCS regime when 0 F E E  and deep in the BEC regime when 0 F E E  .…”

Section: Introductionmentioning

confidence: 99%

Evolution of the dynamics of neutral superconductors between BCS and BEC regimes: The variational approach

Chubukov

2018

Low Temperature Physics

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We use variational approach to analyze the evolution of the dynamics of a neutral s-wave superconductor between BCS and BEC regimes. We consider 2D case, when BCS-BEC crossover occurs already at weak coupling and is governed by the ratio of the two scales-the Fermi energy E F and the bound state energy for two fermions in a vacuum, E 0. BCS and BEC regimes correspond to E F >> E 0 and E F << E 0 , respectively. We compute the spectrum of low-energy bosonic excitations and show that the velocity of phase fluctuations remains / 2 F v through BCS-BEC crossover. We also discuss the topological Aφ  term in the effective action.

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Section: Introductionmentioning

confidence: 99%

Evolution of the dynamics of neutral superconductors between BCS and BEC regimes: The variational approach

Chubukov

2018

Low Temperature Physics

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“…This issue has been discussed in the condensed matter context [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28] . and also for optical lattices of ultracold atoms.…”

Section: Introductionmentioning

confidence: 99%

Superconductivity versus bound-state formation in a two-band superconductor with small Fermi energy: Applications to Fe pnictides/chalcogenides and dopedSrTiO3

2016

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We analyze the interplay between superconductivity and the formation of bound pairs of fermions (BCS-BEC crossover) in a 2D model of interacting fermions with small Fermi energy EF and weak attractive interaction, which extends to energies well above EF . The 2D case is special because two-particle bound state forms at arbitrary weak interaction, and already at weak coupling one has to distinguish between bound state formation and superconductivity. We briefly review the situation in the one-band model and then consider two different two-band models -one with one hole band and one electron band and another with two hole or two electron bands. In each case we obtain the bound state energy 2E0 for two fermions in a vacuum and solve the set of coupled equations for the pairing gaps and the chemical potentials to obtain the onset temperature of the pairing, Tins and the quasiparticle dispersion at T = 0. We then compute the superfluid stiffness ρs(T = 0) and obtain the actual Tc. For definiteness, we set EF in one band to be near zero and consider different ratios of E0 and EF in the other band. We show that, at EF E0, the behavior of both two-band models is BCS-like in the sense that Tc ≈ Tins EF and ∆ ∼ Tc. At EF < E0, the two models behave differently: in the model with two hole/two electron bands, Tins ∼ E0/ log1/2 , and Tc ∼ EF , like in the one-band model. In between Tins and Tc the system displays preformed pair behavior. In the model with one hole and one electron band, Tc remains of order Tins, and both remain finite at EF = 0 and of order E0. The preformed pair behavior still does exist in this model because Tc is numerically smaller than Tins. For both models we re-express Tins in terms of the fully renormalized two-particle scattering amplitude by extending to two-band case the method pioneered by Gorkov and Melik-Barkhudarov back in 1961. We apply our results for the model with a hole and an electron band to Fe-pnictides and Fe-chalcogenides in which superconducting gap has been detected on the bands which do not cross the Fermi level, and to FeSe, in which superconducting gap is comparable to the Fermi energy. We apply the results for the model with two electron bands to Nb-doped SrTiO3 and argue that our theory explains rapid increase of Tc when both bands start crossing the Fermi level.

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“…Similar fluctuation effects have been also reported for the thin samples of the strongly disordered s-wave superconductors * Electronic address: doman@kft.umcs.lublin.pl [18]. These physical processes have been studied within the diagrammatic approximation for the current-current response function, using the dressed single particle propagators [19][20][21], imposing the selfconsistent conserving scheme [22] or inventing other sophisticated methods for the vertex corrections [23,24].…”

Section: Introductionmentioning

confidence: 67%

Fluctuation conductivity due to the preformed local pairs

Domański

Barańska

Solovjov

2016

Low Temperature Physics

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We investigated the properties of a system where the itinerant electrons coexist and interact with the preformed local pairs. Using the nonperturbative continuous unitary transformation technique we show that Andreev-type scattering between these charge carriers gives rise to the enhanced diamagnetic response and is accompanied by appearance of the Drude peak inside the pseudogap regime ω ≤ 2∆ pg . Both effects are caused by the short-range superconducting correlations above the transition temperature T c . In fact, the residual diamagnetism has been detected by the torque magnetometry in the lanthanum and bismuth cuprate superconductors at temperatures up to ~ 1.5T c . In this work we show how the superconducting correlations can be observed in the ac and dc conductivity.

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Current-current Fermi-liquid corrections to the superconducting fluctuations on conductivity and diamagnetism

Cited by 11 publications

References 22 publications

Evolution of the dynamics of neutral superconductors between BCS and BEC regimes: The variational approach

Evolution of the dynamics of neutral superconductors between BCS and BEC regimes: The variational approach

Superconductivity versus bound-state formation in a two-band superconductor with small Fermi energy: Applications to Fe pnictides/chalcogenides and dopedSrTiO3

Fluctuation conductivity due to the preformed local pairs

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