Structural and Superconducting Properties of RE1 - 2xPrxCaxSr0.8Ba1.2Cu3O7 - δ (RE = Er and Gd) High Tc Superconductors

2003 ◽  
Vol 17 (13) ◽  
pp. 2609-2622 ◽  
Author(s):  
N. Charoenthai ◽  
P. Winotai ◽  
R. Suryanarayanan ◽  
I. M. Tang
Keyword(s):  
Heat Treatment ◽  
High Temperature ◽  
Transition Temperature ◽  
Size Effect ◽  
High Temperature Superconductors ◽  
Superconducting Properties ◽  
High Tc Superconductors ◽  
High Tc ◽  
Oxygen Annealing ◽  
Ion Size

We report here on the structural and superconducting properties of RE 1 - 2x Pr x Ca x Sr 0.8 Ba 1.2 Cu 3 O 7 - δ (RE = Er and Gd, 0 ≤ x ≤ 0.2) high temperature superconductors. The transition temperature (Tc) of these compounds decreases when the Pr and Ca concentrations are increased. At constant Pr and Ca concentrations, the Tc of Er 1 - 2x Pr x Ca x Sr 0.8 Ba 1.2 Cu 3 O 7 - δ superconductor system is higher than that observed for the Gd 1 - 2x Pr x Ca x Sr 0.8 Ba 1.2 Cu 3 O 7 - δ system. For the Gd 0.8 Pr 0.1 Ca 0.1 Sr 0.8 Ba 1.2 Cu 3 O 7 - δ sample, after heating in argon followed by oxygen annealing, the orthorhombicity increases accompanied by 10 K increase in Tc. These results show that though our data indicate an ion-size effect, the Tc suppression rate dTc/dx depends very much on the heat treatment adopted to prepare the samples.

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.

SEPARATED SPIN AND CHARGE DEGREES OF FREEDOM IN HIGH-Tc SUPERCONDUCTORS

2005 ◽  
Vol 19 (01n03) ◽  
pp. 193-197
Author(s):  
L. KRUSIN-ELBAUM ◽  
T. SHIBAUCHI ◽  
G. BLATTER
Keyword(s):  
High Temperature ◽  
Magnetic Fields ◽  
Fermi Surface ◽  
Degrees Of Freedom ◽  
High Temperature Superconductors ◽  
Energy Scale ◽  
High Tc Superconductors ◽  
Critical Fields ◽  
High Tc

Recent Nernst and interlayer transport experiments in Bi 2 Sr 2 CaCu 2 O 8+y (BSCCO) high temperature superconductors report hugely different limiting magnetic fields. We demonstrate that both fields convert to the same pseudogap energy scale T* upon transformation as orbital and Zeeman critical fields, respectively. We suggest a consistent interpretation of this finding based on separation of spin and charge degrees of freedom residing in different regions of a truncated Fermi surface.

Superconducting Properties of Substituted Oxides Bi2Sr2−xLaxCuO6+y and Bi2Sr2Ca1−xYxCu2O8+y Neutron Diffraction of Bi2Sr1.6La0.4CuO6+y and Bi2CaLaCuO6+y

1989 ◽  
Vol 156 ◽  
Author(s):  
J. Darriet ◽  
J. A. Alonso ◽  
P. Burlet ◽  
B. Chevalier ◽  
B. Lepine ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Solid Solution ◽  
Critical Temperature ◽  
Neutron Diffraction ◽  
Positive Charge ◽  
Superconducting Transition ◽  
Superconducting Properties ◽  
High Tc Superconductors ◽  
High Tc ◽  
Zero Resistance

ABSTRACTThe substituted oxides Bi2Sr2−xLaxCuO6+y and Bi2Sr2Ca1−xYxCu2O8+y isostructural to the n = 1 and n = 2 members of the high Tc superconductors have been prepared. The solid solution Bi2Sr2−xLaxCuO6+y shows a superconducting transition for 0.2–0.25<x<0.5 with an onset Tc near 30K and zero resistance temperatures which depend on x and the heat treatment. For x = 1 the isostructural phases Bi2ALaCuO6.5+y with A = Ca or Ba have also been synthesized and are not superconducting. A modelfor the localization of the oxygen atoms is proposed based on neutron diffraction of Bi2Sr1.6La0.4CuO6+y and Bi2CaLaCuO6+y.The Bi2Sr2Ca1−xYxCu2O8+y solid solution exhibits a superconducting transition for 0<x <0.7. The critical temperature remains almost constant (85–90K) for 0<x <0.3 and then decreases rapidly. The oxygen content value 8.65 for Bi2Sr2YCu2O8+y agrees well with the increase of the positive charge when calcium is replaced by yttrium.

scholarly journals An Analysis of Strong Coupling in the High Tc Superconductors

2014 ◽  
Vol 2014 ◽  
pp. 1-7
Author(s):  
J. H. Turner
Keyword(s):  
High Temperature ◽  
Strong Coupling ◽  
High Temperature Superconductors ◽  
High Tc Superconductors ◽  
High Tc ◽  
Cubic Symmetry

A new McMillan formula is assembled for the High Temperature Superconductors that evidences strong coupling in these materials. The McMillan-Hopfield parameter is calculated in each case, in addition to the Bergmann and Rainer enhancement frequency. The cubic symmetry of the CuO layers and the lattice cohesion and oxygen presence are suggested reasons for the effect.

THE SURFACE IMPEDANCE OF HIGH Tc SUPERCONDUCTORS

1989 ◽  
Vol 03 (01) ◽  
pp. 5-13 ◽  
Author(s):  
J. CARINI ◽  
L. DRABECK ◽  
G. GRÜNER
Keyword(s):  
High Temperature ◽  
Temperature Dependence ◽  
Power Law ◽  
Surface Impedance ◽  
Low Temperatures ◽  
Qualitative Agreement ◽  
Surface Resistance ◽  
High Temperature Superconductors ◽  
High Tc Superconductors ◽  
High Tc

Recent experiments on the surface impedance of the high temperature superconductors are summarized. The overall temperature dependence of the penetration depth is in broad qualitative agreement with conventional pairing, but with an anomolous power law behavior observed at low temperatures. The surface resistance is orders of magnitude larger than estimates based on the Mattis-Bardeen theory. One possibility is unconventional pairing, but structural inhomogenities are the most likely explanation for the experimental results.

NQR and NMR in High Tc Superconductors

1992 ◽  
Vol 47 (1-2) ◽  
pp. 7-11 ◽  
Author(s):  
K. Asayama ◽  
Y. Kitaoka ◽  
G.-q. Zheng
Keyword(s):  
High Temperature ◽  
Transition Temperature ◽  
Low Temperature ◽  
Spin Fluctuations ◽  
Superconducting Transition ◽  
High Tc Superconductors ◽  
High Tc ◽  
Pairing Correlations ◽  
Antiferromagnetic Spin ◽  
D Wave

AbstractRecent NQR and NMR experiments on La2-xSrxCuO4 , YBa2Cu3O7 , Tl2Ba2CuO6+y , and other compounds are reviewed. The antiferromagnetic spin fluctuations decrease in the order of La, Y, T1 compounds. In the normal state the T-dependence of (T1T)-1 is considered to follow the Curie- Weiss law at high temperature and the (Ti 7") = const law at low temperature. The T dependence of 1/T1 below Tc suggests strongly d-wave pairing. Correlations of the NQR frequency of 63Cu and 17O with the antiferromagnetic spin fluctuations and the superconducting transition temperature are discussed.

What Can we Learn from Magnetization Experiments on HIGH-TC Superconductors? an Overview

1992 ◽  
Vol 275 ◽  
Author(s):  
J. R. Thompson
Keyword(s):  
High Temperature ◽  
Mixed State ◽  
High Temperature Superconductors ◽  
Critical Currents ◽  
High Tc Superconductors ◽  
High Tc ◽  
Convenient Means ◽  
Current Densities ◽  
Types Of Information ◽  
Insight Into

ABSTRACTMagnetization studies provide a facile and convenient means for investigating high temperature superconductors. This work provides an overview and some specific examples of the types of information attainable through magnetic experiments. Regimes to be discussed include the Meissner region with low applied magnetic fields; the mixed state in higher fields at high temperatures, where equilibrium superconductive properties are accessible; and the magnetically irreversible mixed state at lower temperatures, often with large critical current densities Jc. Generally, the critical currents in the last region are metastable. The associated flux creep phenomenon also provides insight into the materials problem of optimizing the pinning of vortices, in order to maximize Jc.

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