Electrodynamic and microwave properties of high-temperature superconductors: Model calculations for coupled weak links

1989 ◽  
Vol 162-164 ◽  
pp. 1593-1594 ◽  
Author(s):  
K.H. Lee ◽  
T.-K. Xia ◽  
D. Stroud
Keyword(s):  
High Temperature ◽  
High Temperature Superconductors ◽  
Microwave Properties ◽  
Weak Links ◽  
Model Calculations

THE MULTILAYERED HIGH Tc SUPERCONDUCTORS; THE JOSEPHSON MODEL OF WEAK LINKS

1995 ◽  
Vol 09 (21) ◽  
pp. 2811-2820
Author(s):  
VALERY A. CHERENKOV
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
High Temperature Superconductors ◽  
Weak Links ◽  
High Tc Superconductors ◽  
Main Attention ◽  
Multilayered Structures ◽  
High Tc ◽  
Stimulation Of

The multilayered (N-S(D)-N)-types structures have been observed: there are the traditional Niobium low-temperature superconductors and new high-temperature superconductors. The main attention had been directed to the anisotropy, defectively and the stimulation of the superconductivity in the multilayered structures.

Mesoscopic Structures and Their Effects on High-Tc Superconductivity

2017 ◽  
Author(s):  
H. Zhang
Keyword(s):  
High Temperature ◽  
Rock Salt ◽  
High Temperature Superconductors ◽  
Structural Features ◽  
X Ray Diffraction ◽  
Model Calculations ◽  
High Tc ◽  
High Tc Superconductivity ◽  
Electron Phonon Coupling ◽  
Structural Blocks

This article presents the results of model calculations carried out to determine the mesoscopic structural features of high-temperature superconducting (HTS) crystal structures, and especially their characteristic high critical temperature (Tc) and anisotropy. The crystal structure of high-temperature superconductors (HTSc) is unique in having some mesoscopic features. For example, the structures of a majority of cuprite superconductors are comprised of two structural blocks, perovskite and rock salt, stacked along the c-direction. This article calculates the interaction between the perovskite and rock salt blocks in the form of combinative energy in order to elucidate the effects of mesoscopic structures on high-Tc superconductivity. Both X-ray diffraction and Raman spectroscopy show that a ‘fixed triangle’ exists in the samples under investigation. The article also examines the importance of electron–phonon coupling in high-Tc superconductors.

Magnetic-history-dependent critical currents in granular high-temperature superconductors: Dependence on defect structures and morphology

1989 ◽  
Vol 47 ◽  
pp. 186-187
Author(s):  
Martin P. Maley ◽  
Michael E. McHenry ◽  
Jeffrey O. Willis
Keyword(s):  
High Temperature ◽  
Critical Current ◽  
High Temperature Superconductors ◽  
Critical Currents ◽  
Weak Links ◽  
Small Scale ◽  
Defect Structures ◽  
Flux Lattice ◽  
Superconducting Coherence Length ◽  
Current Densities

Critical current densities, Jc’s, in conventional low temperature superconductors are controlled by defect structures that provide pinning for the magnetic flux lattice. High critical current densities and strong pinning have been observed in single crystals of the new oxide, high temperature superconductors (HTS) and have been ascribed to the presence of twin planes and to stoichiometry variations in the YBCO compound. Neutron irradiation studies have shown that intragranular Jc’s in YBCO can be strongly enhanced by the point defects introduced by irradiation. However, transport Jc’s determined by intergranular current transfer have remained dissappointingly low in bulk ceramic HTS materials. This has suggested a model of strongly superconducting grains separated by “weak links” that behave as Josephson tunnel junctions.The extraordinarily small superconducting coherence length ζo ∼ 10 A° in the HTS make them considerably more sensitive to small scale defects. Grain boundaries that act as pinning centers in conventional superconductors thus become barriers to current flow in the HTS.

Theory of renormalized phonon group velocity in high-temperature superconductors

2019 ◽  
Vol 33 (27) ◽  
pp. 1950337
Author(s):  
Sanjeev K. Verma ◽  
Anushri Gupta ◽  
Anita Kumari ◽  
B. D. Indu
Keyword(s):  
High Temperature ◽  
Group Velocity ◽  
Quantum Dynamics ◽  
Phonon Frequency ◽  
Phonon Dispersion ◽  
High Temperature Superconductors ◽  
Model Calculations ◽  
Phonon Group Velocity ◽  
Frequency Temperature ◽  
Phonon Dispersion Relations

The expressions for the renormalized phonon group velocity (RPGV) has been developed from renormalized phonon dispersion relations obtained with the help of impurity-induced anharmonic quantum dynamics of phonons via Green’s functions. It is observed that RPGV shows dependence on doping, phonon frequency, temperature, and anharmonicity. The [Formula: see text] superconductor has been taken for model calculations to successfully apply the new results of RPGV.

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