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AC susceptibility of high temperature superconductors in a critical state model
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In this paper, a critical state model for a granular superconductor is employed to calculate the temperature and AC and DC magnetic field dependence of the complex susceptibility, χ = χ ′ + iχ ″, of a sintered bulk YBa 2 Cu 3 O 7- δ superconductuctor.Abstract:
A critical state model for a granular superconductor is employed to calculate the temperature and AC and DC magnetic field dependence of the complex susceptibility, χ = χ ′ + iχ ″, of a sintered bulk YBa 2 Cu 3 O 7- δ superconductor. Inter granular Josephson vortices are assumed to sweep in and out of the weak-link network while intragranular Abrikosov vortices move in and out of the superconducting grains, both causing bulk pinning hysteresis losses. The predictions of the model for χ′ and χ″ are consistent with experimental data and model parameters which characterize a high temperature granular superconductor can be determined. These parameters are the inter- and intragranular pinning force densities, the fraction of the superconducting grains, the grain size distribution and a London penetration depth which neglects grain anisotropy.read more
Citations
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The flux-line lattice in superconductors
TL;DR: In this article, the authors describe the properties of the triangular flux-line lattice (FLL), which is more or less perturbed by material inhomogeneities that pin the flux lines, and also by thermal fluctuations.
Journal ArticleDOI
The Flux-Line Lattice in Superconductors
TL;DR: In this article, the authors describe the properties of the triangular flux-line lattice (FLL), which is more or less perturbed by material inhomogeneities that pin the flux lines and also by thermal fluctuations.
Journal ArticleDOI
Characterization of high-temperature superconductors by AC susceptibility measurements
TL;DR: In this paper, the authors introduce the wide-band AC susceptibility, the so-called ''wide-band magnetic flux'' which refers to the magnetic flux and often offers an easier meeting between theory and experiment.
Journal Article
Josephson Junction Model of Critical Current in Granular Y1Ba2Cu3O7-δ
TL;DR: In this paper, the transport critical-current density in a granular superconductor in magnetic fields below about 5 x 10/sup -3/T was calculated, and it was shown that Josephson junctions are limiting transport critical current in these samples and that they lie at the grain boundaries.
Journal ArticleDOI
Flux line lattice in high-Tc superconductors: anisotropy, elasticity, fluctuation, thermal depinning, AC penetration and susceptibility
TL;DR: In this paper, various properties of the flux-line lattice (FLL) in high-T c superconductors are compiled, derived, and discussed, and useful general and updated expressions for the energy and magnetic field of arbitrary flux line arrangements in anisotropic and layered supercondors are presented.
References
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Journal ArticleDOI
Theory of Flux Creep in Hard Superconductors
TL;DR: In this paper, the authors show that the mechanism of flux creep is thermally activated motion of bundles of flux lines, aided by the Lorentz force, over free energy barriers coming from the pinning effect of inhomogeneities, strains, dislocations, or other physical defects.
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Critical persistent currents in hard superconductors
TL;DR: In this paper, the authors investigated persistent currents induced in hard superconductors (HSC) by measuring the resulting magnetic effects and found that the Lorentz force plays a crucial role in determining the critical current density and the critical persistent currents in decay with a measurable rate.
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Granular and superconducting-glass properties of the high-temperature superconductors
TL;DR: In this article, a simple theoretical model for the granularity is introduced and then used to discuss a number of electrodynamic properties (hysteretic magnetization versus magnetic field, zero-field-cooled and field cooled magnetisation versus temperature, ac susceptibility, and flux creep with logarithmic time dependence).
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Josephson-junction model of critical current in granular Y 1 Ba 2 Cu 3 O 7 − δ superconductors
TL;DR: It is concluded that Josephson junctions are limiting the transport critical current in these samples and that they lie at the grain boundaries.