Weak links and the poor transport critical currents of the 123 compounds

Larbalestier, D. C.; Babcock, S.E.; Cai, X. Y.; Daeumling, M.; Hampshire, D.P.; Kelly, Tom; LaVanier, Lori A.; Lee, Peter J.; Seuntjens, J. M.

doi:10.1016/0921-4534(88)90426-1

Cited by 58 publications

(11 citation statements)

References 19 publications

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“…It may have caused to deterioration of the transport properties of RE = Sm and Nd. We must note that these J c values are approximately the same as the values reported for RE = 123 [31].…”

Section: Resultssupporting

confidence: 50%

The Role of Oxygenation on Superconducting Properties of RE3Ba5Cu8O18 (RE=Y, Sm and Nd) Compounds

Topal

Akdoğan

2011

J Supercond Nov Magn

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This study reports the effects of oxygenation on new high-T c cuprates having the structure of RE 3 Ba 5 Cu 8 O 18 (RE = Y, Sm and Nd) and T c (on) values of 96.5-97.5 K. The measurements have shown that excess oxygenation has no important contribution to the T c (on) values, but it improves T c (off) values significantly. From these three systems, RE = Nd is the most sensitive one to the oxygenation. Its T c (off) value increases by 13 K (from 78 K to 91.1 K) with post-annealing.

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“…It may have caused to deterioration of the transport properties of RE = Sm and Nd. We must note that these J c values are approximately the same as the values reported for RE = 123 [31].…”

Section: Resultssupporting

confidence: 50%

The Role of Oxygenation on Superconducting Properties of RE3Ba5Cu8O18 (RE=Y, Sm and Nd) Compounds

Topal

Akdoğan

2011

J Supercond Nov Magn

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“…The typical value of the critical current density for ceramic superconductors is ∼ 10 6 A/m 2 ( see, for example, Ref. [280,[288][289][290]). Since the typical size of grains is about 1µm we have the critical current I c ∼ 10 −6 A.…”

Section: Anomalous Microwave Absorptionmentioning

confidence: 99%

Paramagnetic Meissner effect and related dynamical phenomena

2003

Physics Reports

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The hallmark of superconductivity is the diamagnetic response to external magnetic field. In striking contrast to this behavior, a paramagnetic response or paramagnetic Meissner effect was observed in ceramic high-Tc and in conventional superconductors. The present review is given on this interesting effect and related phenomena. We begin with a detailed discussion of experimental results on the paramagnetic Meissner effect in both granular and conventional superconductors. There are two main mechanisms leading to the paramagnetic response: the so called d-wave and the flux compression. In the first scenario, the Josephson critical current between two d-wave superconductors becomes negative or equivalently one has a π junction. The paramagnetic signal occurs due to the nonzero spontaneous supercurrent circulating in a loop consisting of odd number of π junctions. In addition to the d-wave mechanism we present the flux compression mechanism for the paramagnetic Meissner effect. The compression may be due to either an inhomogeneous superconducting transition or flux trap inside the giant vortex state. The flux trapping which acts like a total nonzero spontaneous magnetic moment causes the paramagnetic signal. The anisotropic pairing scenario is believed to be valid for granular materials while the flux trap one can be applied to both conventional and high-Tc superconductors. The study of different phenomena by a three-dimensional lattice model of randomly distributed π Josephson junctions with finite self-inductance occupies the main part of our review. By simulations one can show that the chiral glass phase in which chiralities are frozen in time and in space may occur in granular superconductors possessing d-wave pairing symmetry. Experimental attempts on the search for the chiral glass phase are analysed. Experiments on dynamical phenomena such as AC susceptibility, compensation effect, anomalous microwave absorption, aging effect, AC resistivity and enhancement of critical current by external electric fields are considered. These phenomena were studied by Monte Carlo and Langevin dynamics simulations which show satisfactory agreement with experiments. We present a resistively shunted junction model describing rich dynamics of Josephson junction networks.

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“…The smaller the grain size is, the higher is Jc. A decrease in grain size leads to an increase in the number of junctions, thus making more percolative paths available for current flow [104]. Secondly, due to the Josephson penetration depth of the current in the junction, the effective surface for current transport is weaker for large junctions than for small ones [105].…”

Section: Grain Boundaries In Bulk and Transport Propertiesmentioning

confidence: 99%

Grain boundaries in high temperature superconducting ceramics

Ayache

2006

Philosophical Magazine

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International audienceThe aim of this paper is to review the different types of grain boundaries found in YBa₂Cu₃O_7-d superconducting ceramics which have been investigated over the past decade. A variety of samples covering a wide range of current density Jc values are examined including: classical bulk ceramics, melt-textured bulk ceramics, bulk and thin film bicrystals with specific orientations, thin films and single crystals. From electronic coupling, Jc is expected and found to decrease with increasing grain boundary (GB) misorientation. From the magnetic behaviour, the critical current density Jc(H) is expected to increase with the number of pinning centres. The properties of the various types of GB's are discussed. All the studies reviewed lead to the conclusion that grain boundaries in YBCO materials cannot be understood without specific information about their local composition, structure and electronic state. They confirm that research on bicrystals is crucial for high-temperature superconductor development

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Weak links and the poor transport critical currents of the 123 compounds

Cited by 58 publications

References 19 publications

The Role of Oxygenation on Superconducting Properties of RE3Ba5Cu8O18 (RE=Y, Sm and Nd) Compounds

The Role of Oxygenation on Superconducting Properties of RE3Ba5Cu8O18 (RE=Y, Sm and Nd) Compounds

Paramagnetic Meissner effect and related dynamical phenomena

Grain boundaries in high temperature superconducting ceramics

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