Superconductivity in a system with preformed pairs

Geshkenbeǐn, V. B.; Ioffe, L. B.; Larkin, A. I.

doi:10.1103/physrevb.55.3173

Cited by 294 publications

(327 citation statements)

References 38 publications

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“…A nice summary of the experimental support for this viewpoint, (principally based on the observed narrow fluctuation regime), can be found in Ref. [16]. The key assumption underlying our theoretical approach is that the ground state is of the generalized BCS form with wave-function…”

Section: Cond-mat/0107275mentioning

confidence: 99%

The origin of the pseudogap phase: precursor superconductivity versus a competing energy gap scenario

Levin

Chen

Kosztin

et al. 2002

Journal of Physics and Chemistry of Solids

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In the last few years evidence has been accumulating that there are a multiplicity of energy scales which characterize superconductivity in the underdoped cuprates. In contrast to the situation in BCS superconductors, the phase coherence temperature Tc is different from the energy gap onset temperature T * . In addition, thermodynamic and tunneling spectroscopies have led to the inference that the order parameter ∆sc is to be distinguished from the excitation gap ∆; in this way, pseudogap effects persist below Tc. It has been argued by many in the community that the presence of these distinct energy scales demonstrates that the pseudogap is unrelated to superconductivity. In this paper we show that this inference is incorrect. We demonstrate that the difference between the order parameter and excitation gap and the contrasting dependences of T * and Tc on hole concentration x and magnetic field H follow from a natural generalization of BCS theory. This simple generalized form is based on a BCS-like ground state, but with self consistently determined chemical potential in the presence of arbitrary attractive coupling g. We have applied this mean field theory with some success to tunneling, transport, thermodynamics and magnetic field effects. We contrast the present approach with the phase fluctuation scenario and discuss key features which might distinguish our precursor superconductivity picture from that involving a competing order parameter. cond-mat/0107275One of the biggest questions which faces the high temperature superconductivity community is determining the origin of the pseudogap phase. It is now becoming clear that pseudogap effects are not restricted to the normal state alone. Moreover, they appear to persist over a wide range of the phase diagram, up to and possibly above optimal doping [1]. Understanding the pseudogap phase is essential in order to find a proper replacement for BCS theory. Indeed, the failure of BCS theory is demonstrated most clearly in thermodynamical[2] and tunneling[3] data which have made it clear that the underlying normal phase below T c contains a (pseudo)gap in the excitation spectrum. The phase diagram, itself, indicates that the larger the pseudogap the lower is T c and in this way the pseudogap appears to compete with superconductivity. This competition has led many researchers to argue that T c and T * must necessarily originate from different physical mechanisms. A recent D-density wave (DDW) theory[4] presents a concrete realization of the "competing energy gap" scenario, first conjectured by Loram and co-workers [2].The present paper summarizes work from our group [5][6][7][8][9][10] which is based on a precursor superconductivity approach to understanding the pseudogap phase. We have been arguing for some time now that pseudogap effects necessarily persist below T c , and moreover, appear to compete with superconductivity -despite their common origin. Our approach is based on a simple physical picture [11] which interpolates smoothly between BCS theory and Bose Ei...

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Section: Cond-mat/0107275mentioning

confidence: 99%

The origin of the pseudogap phase: precursor superconductivity versus a competing energy gap scenario

Levin

Chen

Kosztin

et al. 2002

Journal of Physics and Chemistry of Solids

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“…12͒. [25][26][27][28][29][30][31][32] This heterogeneous structure of the Fermi surface in the pseudogap regime can provide a possible reason why parts of quasiparticle and/or hole-pair states become inhomogeneous in the intense, pinned 4a ϫ 4a charge order state; the incoherent electronic states around the antinodes, where the pseudogap develops at T Ͼ T c , are easily modified by external perturbation caused by the randomness associated with pinning potential of the charge order.…”

Section: Pinned 4a ã 4a Charge Order and Inhomogeneous Gap Structurementioning

confidence: 99%

Scanning tunneling microscopy and spectroscopy study of4a×4aelectronic charge order and the inhomogeneous pairing gap in superconductingBi2
Hashimoto
¹
,
Momono
²
,
Oda
³

et al. 2006
Phys. Rev. B
37
1
32
0
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We performed scanning tunneling microscopy and scanning tunneling spectroscopy ͑STS͒ measurements on underdoped Bi2212 crystals with doping levels p ϳ 0.11, ϳ0.13, and ϳ0.14 to examine the nature of the nondispersive 4a ϫ 4a charge order in the superconducting state at T Ӷ T c . The charge order appears conspicuously within the pairing gap, and low doping tends to favor the charge order. We point out the possibility that the 4a ϫ 4a charge order will be dynamical in itself, and pinned down over regions with effective pinning centers. The pinned 4a ϫ 4a charge order is closely related to the spatially inhomogeneous pairing gap structure, which has often been reported in STS measurements on high-T c cuprates.

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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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Superconductivity in a system with preformed pairs

Cited by 294 publications

References 38 publications

The origin of the pseudogap phase: precursor superconductivity versus a competing energy gap scenario

The origin of the pseudogap phase: precursor superconductivity versus a competing energy gap scenario

Scanning tunneling microscopy and spectroscopy study of4a×4aelectronic charge order and the inhomogeneous pairing gap in superconductingBi2
Hashimoto
¹
,
Momono
²
,
Oda
³

et al. 2006
Phys. Rev. B
37
1
32
0
View full text Add to dashboard Cite

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

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Superconductivity in a system with preformed pairs

Cited by 294 publications

References 38 publications

The origin of the pseudogap phase: precursor superconductivity versus a competing energy gap scenario

The origin of the pseudogap phase: precursor superconductivity versus a competing energy gap scenario

Scanning tunneling microscopy and spectroscopy study of4a×4aelectronic charge order and the inhomogeneous pairing gap in superconductingBi2Hashimoto1, Momono2, Oda3 et al. 2006Phys. Rev. B371320View full textAdd to dashboardCite

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

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Product

Resources

About

Scanning tunneling microscopy and spectroscopy study of4a×4aelectronic charge order and the inhomogeneous pairing gap in superconductingBi2
Hashimoto
¹
,
Momono
²
,
Oda
³

et al. 2006
Phys. Rev. B
37
1
32
0
View full text Add to dashboard Cite

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