Pairing interactions and pairing mechanism in high-temperature copper oxide superconductors

Zhao, Guangyao

doi:10.1103/physrevb.71.104517

Cited by 9 publications

(3 citation statements)

References 85 publications

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“…For example, the energy of the dip feature in the tunneling spectrum of BSCCO is found to be about 45 meV [51], close to the magnetic resonance energy of about 43 meV [63]. However, the inversion of the same tunneling spectrum [51] yields a very strong coupling feature at about 20 meV, in quantitative agreement with the mode energies of several overdoped BSCCO crystals inferred from the electron self-energies along the antinodal direction [64]. Furthermore, this theoretical prediction also contradicts more recent atomic-resolution tunneling spectra in various BSCCO crystals.…”

Section: Strong Coupling To Multiple-phonon Modes In Arpes and Tunnel...supporting

confidence: 76%

The pairing mechanism of high-temperature superconductivity: experimental constraints

Zhao¹

2011

Phys. Scr.

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Developing a theory of high-temperature superconductivity in copper oxides is one of the outstanding problems in physics. It is a challenge that has defeated theoretical physicists for more than twenty years. Attempts to understand this problem are hindered by the subtle interplay among a few mechanisms and the presence of several nearly degenerate and competing phases in these systems. Here we present some crucial experiments that place essential constraints on the pairing mechanism of high-temperature superconductivity. The observed unconventional oxygenisotope effects in cuprates have clearly shown strong electron-phonon interactions and the existence of polarons and/or bipolarons. Angle-resolved photoemission and tunneling spectra have provided direct evidence for strong coupling to multiple-phonon modes. In contrast, these spectra do not show strong coupling features expected for magnetic resonance modes. Angle-resolved photoemission spectra and the oxygen-isotope effect on the antiferromagnetic exchange energy J in undoped parent compounds consistently show that the polaron binding energy is about 2 eV, which is over one order of magnitude larger than J = 0.14 eV. The normal-state spin-susceptibility data of holedoped cuprates indicate that intersite bipolarons are the dominant charge carriers in the underdoped region while the component of Fermi-liquid-like polarons is dominant in the overdoped region. All the experiments to test the gap or order-parameter symmetry consistently demonstrate that the intrinsic gap (pairing) symmetry for the Fermi-liquid-like component is anisotropic s-wave and the order-parameter symmetry of the Bose-Einstein condensation of bipolarons is d-wave. BCS THEORY AND THE CONVENTIONAL ISOTOPE EFFECT ON TcIn 1911 curiosity concerning the electrical properties of metals at low temperatures led the Dutch physicist, H. K. Onnes and his assistant G. Holst to discover superconductivity at 4.2 K in mercury [1]. This discovery was one of the most important experimental findings in low temperature physics. Since then tremendous theoretical and experimental efforts have been made with the aim of clarifying the microscopic mechanism responsible for this novel ground state.On the long way towards a microscopic understanding of superconductivity, the observation of an isotope effect on T c in 1950 [2,3] gave important clues to the understanding of the microscopic theory of superconductivity. The presence of an isotope effect thus implies that superconductivity is not of purely electronic origin. In the same year H. Fröhlich [4] pointed out that the electronphonon interaction gave rise to an indirect attractive interaction between electrons, which might be responsible for superconductivity. Fröhlich's theory played a decisive role in establishing the correct mechanism. Later, in 1956 L. Cooper [5] discovered that electrons with an attractive interaction form bound pairs (so called Cooper pairs) which lead to superconductivity. However, the existence of electron pairs does not necessarily imply a...

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Section: Strong Coupling To Multiple-phonon Modes In Arpes and Tunnel...supporting

confidence: 76%

The pairing mechanism of high-temperature superconductivity: experimental constraints

Zhao¹

2011

Phys. Scr.

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“…It is remarkable that, for hole-and electron-doped cuprates, there is still no clarity concerning the specific mechanisms of superconductivity [17,[107][108][109][110][111][112][113][114][115] and the order parameter symmetry [109,[116][117][118][119][120][121][122][123][124][125][126][127][128][129][130], contrary to the "official" viewpoint [131][132][133]) and even the very character of the phenomenon (in particular, there have been furious debates concerning the Cooper pairing versus boson condensation dilemma in cuprates [8,134,135]). The same seems to be true for other old and new "exotic" superconductors [46,107,108,[136][137][138][139][140][141][142][143][144][145][146]…”

Section: Introductionmentioning

confidence: 99%

Competition of Superconductivity and Charge Density Waves in Cuprates: Recent Evidence and Interpretation

Gabovich

Войтенко

Ekino

et al. 2010

Advances in Condensed Matter Physics

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Explicit and implicit experimental evidence for charge density wave (CDW) presence in high-Tcsuperconducting oxides is analyzed. The theory of CDW superconductors is presented. It is shown that the observed pseudogaps and dip-hump structures in tunnel and photoemission spectra are manifestations of the same CDW gapping of the quasiparticle density of states. Huge pseudogaps are transformed into modest dip-hump structures at low temperatures,T, when the electron spectrum superconducting gapping dominates. Heat capacity jumps at the superconducting critical temperature and the paramagnetic limit are calculated for CDW superconductors. For a certain range of parameters, the CDW state in ad-wave superconductor becomes reentrant withT, the main control quantity being a portion of dielectrcally gapped Fermi surface. It is shown that in the weak-coupling approximation, the ratio between the superconducting gap at zero temperatureΔ(T=0)andTchas the Bardeen-Cooper-Schrieffer value fors-wave Cooper pairing and exceeds the corresponding value ford-wave pairing of CDW superconductors. Thus, large experimentally found values2Δ(T=0)/Tc≈5÷8are easily reproduced with reasonable input parameter values of the model. The conclusion is made that CDWs play a significant role in cuprate superconductivity.

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“…In spite of the great efforts spent by researches in order to explain conduction inY 123 , till now there is no agreement about model for conduction in Y 123 compound. Efforts on substitution in high temperature superconductors (HTSC) from their initial discovery lead to great improvement in and to the discoveries of new high temperature superconductors, HTSC (Zhao, 2005), ( McCormack and de Fontaine., 1992).…”

Section: Introductionmentioning

confidence: 99%

Investigating Effect of Ca Content on Electrostatic Potential Energy (EP), Critical Temperature and Structure Parameters on Superconductor

Mustafa¹,

Rostam²

2018

RJS

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In this paper the effect of Ca content in and the relation between electrostatic potential energy, critical temperature lattice parameters , volume lattice parameter , orthorhombicity, and the hole concentration is investigated by applying the ionic model to calculate the change in the electrostatic potential due to increasing the Ca content in the compound in. It is found that Ca 2+ substitution for Y 3+ leads to increase EP caused by increased ion volume and decrease of charge, this explains changes of superconducting structure parameters such as: lattice parameter ,volume lattice parameter , orthorhombicity. Furthermore decreases with increasing Ca content due to increase of EP which leads to change of the crystal structure and thus decreasing oxygen content and as a result decreasing of Finally considering all above effects the increase of EP will increase the superconducting current.

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Pairing interactions and pairing mechanism in high-temperature copper oxide superconductors

Cited by 9 publications

References 85 publications

The pairing mechanism of high-temperature superconductivity: experimental constraints

The pairing mechanism of high-temperature superconductivity: experimental constraints

Competition of Superconductivity and Charge Density Waves in Cuprates: Recent Evidence and Interpretation

Investigating Effect of Ca Content on Electrostatic Potential Energy (EP), Critical Temperature and Structure Parameters on Superconductor

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