Pairing Mechanism for the High-TC Superconductivity: Symmetries and Thermodynamic Properties

Szczȩśniak, R.

doi:10.1371/journal.pone.0031873

Cited by 47 publications

(69 citation statements)

References 132 publications

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Section: Introductionmentioning

confidence: 99%

“…In particular, for the selected values of tin content, the dependence of the average amplitude of the energy gap on the temperature and the dependence of the energy gap on the wave vector have been calculated. The numerical analysis has been conducted in the framework of the recently introduced model [4,5].We notice that the model is based on the following postulates: The postulate (i) underlines the importance of the quasi two-dimensionality of the electron system. The second one draws attention to the electron-phonon pairing mechanism given by Fröhlich [6,7].…”

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confidence: 99%

“…Fig. 1 The influence of the tin-induced disorder on the value of the temperature T C and T for Sn-doped Hg-1223 [14] Based on approach presented in the papers [4] and [5], it is possible to prove that the critical temperature uniquely determines the value of the potential for the electron-phonon interaction. On the other hand, the temperature of the pseudogap depends on both the electron-phonon potential and the potential of the electron-electron-phonon interaction.…”

mentioning

confidence: 99%

“…Based on these observations, the averaged value of the amplitude of the energy gap G(T ) ≡ 2 (tot) (T ) can be calculated on the basis of the following expression [4,5]:…”

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confidence: 99%

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The Energy Gap in the (Hg1−x Sn x )Ba2Ca2Cu3O8+y Superconductor

Szczȩśniak

Durajski

2014

J Supercond Nov Magn

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The experimental data show that the increase of tin in the (Hg 1−x Sn x )Ba 2 Ca 2 Cu 3 O 8+y superconductor results in a visible increase in the pseudogap temperature (T ) with a slight decrease in the value of the critical temperature (T C ). Based on the above results, the dependence of the average amplitude of the energy gap on the temperature (G(T )) has been determined for x ∈ 0, 0.25 . On this basis, it has been found that the dimensionless ratio R G ≡ G(0)/k B T C increases with the increasing tin content from the value of 3.48 to the value of 4.88. Next, for x = 0.25 and T ∈ 0, T , the dependence of the energy gap on the wave vector has been calculated in the surrounding of the Fermi level. It has been shown that in the anti-nodal region the energy gap is very weakly dependent on the temperature. On the other hand, in the nodal region its values strongly decrease together with the increasing temperature.Keywords High-T C superconductors · Thermodynamic properties · Electron-phonon couplingThe thermodynamic properties of the superconducting state in cuprates can be determined on the basis of two characteristic types of temperature: T C (the critical temperature) and T (the pseudogap temperature). The first temperature determines the disappearance of the superconducting state; the second one represents the value below which, in the normal state, the pseudogap appears in the electron density of states In the presented paper, the disorder induced by tin in the (Hg 1−x Sn x )Ba 2 Ca 2 Cu 3 O 8+y superconductor (Sndoped Hg-1223) has been considered. In particular, for the selected values of tin content, the dependence of the average amplitude of the energy gap on the temperature and the dependence of the energy gap on the wave vector have been calculated. The numerical analysis has been conducted in the framework of the recently introduced model [4,5].We notice that the model is based on the following postulates: The postulate (i) underlines the importance of the quasi two-dimensionality of the electron system. The second one draws attention to the electron-phonon pairing mechanism given by Fröhlich [6,7]. The third one postulates that the strong electron correlations in the cuprates are coupled with the phonon degrees of freedom. The first two postulates define the van Hove scenario [8][9][10][11][12]. The third postulate requires further discussion because it is far more subtle. In particular, it should be noted that the postulated electron correlations generalize the Hubbard approach [13]; the classical electron-electron interaction is replaced with the electronelectron-phonon coupling.

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Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

“…Based on these observations, the averaged value of the amplitude of the energy gap G(T ) ≡ 2 (tot) (T ) can be calculated on the basis of the following expression [4,5]:…”

mentioning

confidence: 99%

See 2 more Smart Citations

The Energy Gap in the (Hg1−x Sn x )Ba2Ca2Cu3O8+y Superconductor

Szczȩśniak

Durajski

2014

J Supercond Nov Magn

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“…In the presented paper, we have studied the anisotropy of the gap parameter for the hole-doped superconductors in the framework of the recently introduced theory [28], [29].…”

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Anisotropy of the gap parameter in the hole-doped cuprates

Szczȩśniak¹,

Durajski²

2014

Supercond. Sci. Technol.

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The structure of the gap parameter (∆ k ) for the hole-doped cuprates has been studied. The obtained results indicate that the antinodal part of ∆ k is very weakly temperature dependent and above the critical temperature (TC), it extends into the anomalous normal state to the pseudogap temperature. On the other hand, the values of ∆ k , which are close to the nodal part, are strongly temperature dependent. The model has been tested for the YBa2Cu3O 7−δ superconductor. It has been shown that the theoretical results agree with the experimental data.Keywords: High-temperature superconductors; Anisotropy; Energy gap. [20]. So far, the obtained results have been interpreted in the framework of the two different approaches.In the first case, the difference between the doping and temperature dependence of the gap in the nodal and antinodal region suggests that the pseudogap and the superconducting gap are independent [21], [22]. Additional support comes from the strong deviation from the standard d-wave form of the energy gap in the underdoped region. The above fact is interpreted as composition of the d-wave superconducting gap and the remnant pseudogap [23], [24].In the second case, the pseudogap is considered as the precursor of the superconducting gap [25], [26]. The d-wave symmetry deviation in the underdoped region is connected with the existence of the high-harmonic pairing terms [27].In the presented paper, we have studied the anisotropy of the gap parameter for the hole-doped superconductors in the framework of the recently introduced theory [28], [29].Our main purpose was to derivation the thermodynamic equation for the anomalous thermal average, which determines the structure of the gap parameter. Next, the temperature dependence of the nodal and the antinodal part of the energy gap has been calculated. We have assumed that the theory should be simple enough as far as possible. However, the good agreement between the theoretical predictions and the experimental results has been also required.The model is based on three postulates: (i) In the superconductivity domain of the cuprates the fundamental role is played by the electrons on the CuO 2 planes. (ii) The conventional electron-phonon (EPH) interaction exists in the cuprates, which does not have to be strong. (iii) Strong electronic correlations exist in the cuprates, but the electron-electron scattering in the superconductivity domain is inseparably connected with absorption or emission of the vibrational quanta.The first postulate emphasizes the importance of the quasi two-dimensionality of the system. The second one refers to the classical pairing mechanism given by Fröhlich [30], [31]. The third postulate states that the strong electron correlations in the cuprates are inseparably coupled with the phonon subsystem. The first two postulates define the van Hove scenario [32], [33]. The third postulate requires further discussion because it is far more subtle. In particular, it should be noted that the postulated electron correlations generalize the Hubb...

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Pseudogap in the Eliashberg approach based on electron‐phonon and electron‐electron‐phonon interaction

2017

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The properties of the superconducting and the anomalous normal state were described by using the Eliashberg method. The pairing mechanism was reproduced with the help of the Hamiltonian, which models the electron-phonon and the electron-electron-phonon interaction (EEPh). The set of the Eliashberg equations, which determines the order parameter function (ϕ), the wave function renormalization factor (Z), and the energy shift function (χ ), was derived. It was proven that for the sufficiently large values of the EEPh potential, the doping dependence of the order parameter (ϕ/Z) has the analogous course to that observed experimentally in cuprates. The energy gap in the electron density of states is induced by Z and χ -the contribution from ϕ is negligible. The electron density of states possesses the characteristic asymmetric form and the pseudogap is observed above the critical temperature.

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Pairing Mechanism for the High-TC Superconductivity: Symmetries and Thermodynamic Properties

Cited by 47 publications

References 132 publications

The Energy Gap in the (Hg1−x Sn x )Ba2Ca2Cu3O8+y Superconductor

The Energy Gap in the (Hg1−x Sn x )Ba2Ca2Cu3O8+y Superconductor

Anisotropy of the gap parameter in the hole-doped cuprates

Pseudogap in the Eliashberg approach based on electron‐phonon and electron‐electron‐phonon interaction

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