Screening of Low Frequency Electromagnetic Fields by the High-T sub c Superconductor YBa sub 2 Cu sub 3 O sub 7

The temperature and magnetic field dependences of the magnetization and the electromagnetic shielding efficiency in polycrystalline samples of the high-T sub C superconductor YBa sub 2 Cu sub 3 O sub 7-- delta have been studied. At all temperatures investigated, two field regimes can be identified:...

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Bibliographic Details
Published in:Physica scripta 1991-07, Vol.44 (1), p.108-111
Main Authors: Rudner, S, Wernlund, L-D, Svedlindh, P, Norling, P
Format: Article
Language:English
Online Access:Get full text
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Summary:The temperature and magnetic field dependences of the magnetization and the electromagnetic shielding efficiency in polycrystalline samples of the high-T sub C superconductor YBa sub 2 Cu sub 3 O sub 7-- delta have been studied. At all temperatures investigated, two field regimes can be identified: a low field regime with an ideal diamagnetic behaviour and a large shielding factor, and an intermediate field regime, typically above a few mT, with a reduced diamagnetic susceptibility and a poor shielding efficiency. Using arguments from a modified critical state model, with a strongly field dependent critical current density, the transition to the intermediate field regime is attributed to the decoupling of the superconducting grains. It is argued that this effect is caused by the weakening of the intergrain Josephson junctions in the presence of a magnetic field.
ISSN:0031-8949