scholarly journals THEORY OF SINUSOIDAL MODULATION OF THE RESONANT NEUTRON SCATTERING IN HIGH TEMPERATURE SUPERCONDUCTORS

2001 ◽  
Vol 15 (04) ◽  
pp. 373-377
Author(s):  
TAO LI
Keyword(s):  
High Temperature ◽  
Neutron Scattering ◽  
Spin Fluctuation ◽  
High Temperature Superconductors ◽  
S Wave ◽  
Sinusoidal Modulation ◽  
Wave Symmetry ◽  
Superconducting Pairing ◽  
Comparable Magnitude ◽  
Antiferromagnetic Spin

A model with interlayer pairing is proposed to explain the sinusoidal modulation of the resonant neutron scattering in high temperature superconductors. It is found that the interlayer pairing has s-wave symmetry in the CuO 2 plane and has comparable magnitude with the d-wave intralayer pairing. It is also found that the interlayer pairing mainly affects momentum close to the hot spots on the Fermi surface while its effect on the gap nodes is negligible. It is pointed out that these characteristics of the interlayer pairing can be understood in a model in which the superconducting pairing originates from the exchange of the antiferromagnetic spin fluctuation.

scholarly journals Unusual symmetries of the order parameter in cuprates

2020 ◽  
Vol 2 (4) ◽  
pp. 207-212
Author(s):  
Tran Van Luong ◽  
Nguyen Thi Ngoc Nu
Keyword(s):  
High Temperature ◽  
Order Parameter ◽  
Cuprate Superconductors ◽  
High Temperature Superconductivity ◽  
Spin Fluctuation ◽  
High Temperature Superconductors ◽  
Coulomb Repulsion ◽  
Bcs Theory ◽  
S Wave ◽  
Wave Symmetry

The BCS superconducting theory, introduced by J. Bardeen, L. Cooper and R. Schriffer in 1957, succeeded in describing and satis-factorily explaining the nature of superconductivity for low-temperature superconductors. However, the BCS theory cannot explain the properties of high-temperature superconductors, discovered by J. G. Bednorz and K. A. Müller in 1986. Although scientists have found a lot of new superconductors and their transition temperatures are constantly increasing, most high-temperature superconductors are found by experiment and so far no theory can fully explain their properties. Many previous studies have suggested that the order parameter in high-temperature copper-based superconductors (cuprate superconductors - cuprates) is in the form of d-wave symmetry, but recent results show that the order parameter has an extended s-wave symmetry (extended s wave). Studying the symmetric forms of order parameters in cuprate can contribute to understanding the nature of high-temperature superconductivity. In this article, the authors present an overview of the development of high-temperature supercon-ductors over the past 30 years and explains unusual symmetries of the order parameter in copper-based superconductors. The com-petition of three coupling mechanisms of electrons in cuprates (the mechanism of coupling through coulomb repulsion, electron-phonon mechanism and spin-fluctuation mechanism) affects the unusual symmetry of the order parameter. The solution of the self-consistency equation in simple cases has been found and the ability to move the phase within the superconducting state has been shown.

scholarly journals The Gap and the Upper Critical FieldHc2as Function of Doping for High-TcCuprates

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
S. Orozco ◽  
R. M. Méndez-Moreno ◽  
M. A. Ortiz
Keyword(s):  
High Temperature ◽  
Critical Field ◽  
Energy Gap ◽  
High Temperature Superconductors ◽  
Upper Critical Field ◽  
Superconducting Gap ◽  
Phonon Interaction ◽  
As Doping ◽  
Electron Phonon Interaction ◽  
Wave Symmetry

The relation between thed-wave superconducting gapΔ0and the specific heat obtained with the Volovik effect is used to determine the upper critical fieldHc2as doping function, for high-temperature superconductors. A two-components model withd-wave symmetry, within the BCS framework, is introduced to describe the superconducting state. Generalized Fermi surface topologies are used in order to increase the density of states at the Fermi level, allowing the high-Tcvalues observed. The electron-phonon interaction is considered the most relevant mechanism for the high-Tccuprates, where the available phonon energy is provided by the half-breathing modes. The energy gap valuesΔ0calculated with this model are introduced to describe the variation of the upper critical fieldHc2as function of doping, forLa2-xSrxCuO4.

OCCURRENCE OF SPIN-FLUCTUATION PAIRING IN HIGH-TEMPERATURE SUPERCONDUCTORS

1999 ◽  
Vol 13 (29n31) ◽  
pp. 3635-3641 ◽  
Author(s):  
Howard A. Blackstead ◽  
John D. Dow
Keyword(s):  
High Temperature ◽  
Cooper Pair ◽  
Spin Fluctuation ◽  
High Temperature Superconductors ◽  
Wave Pairing ◽  
D Wave

The definitive property of a spin-fluctuation d-wave-pairing superconductor is that cuprate-plane Cu-site Ni is a weaker Cooper-pair-breaker than Zn on the same site. None of the major high-temperature superconductors, except possibly YBa 2 Cu 3 O x, exhibits this property experimentally.

Neutron scattering investigations of the Abrikosov state of high-temperature superconductors

2006 ◽  
Vol 385-386 ◽  
pp. 35-37 ◽  
Author(s):  
J. Chang ◽  
J. Mesot ◽  
R. Gilardi ◽  
J. Kohlbrecher ◽  
A.J. Drew ◽  
...  
Keyword(s):  
High Temperature ◽  
Neutron Scattering ◽  
High Temperature Superconductors
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