The Complex AC Susceptibility — Critical Current Relationship in Oxide Superconductors
The critical currents of the high-temperature superconducting oxides (LaBaCuO & YBaCuO) in either bulk or thin film form are limited by the Josephson coupling between the superconducting grains. This coupling is also reflected in the complex ac susceptibility as a function of the ac magnetic field, h. The inductive component x′ actually consists of an ac field dependent contribution that reflects the coupling strength between the grains and an essentially field independent contribution at larger fields which represents the Meissner state of the grains. The resistive component x″ shows a maximum that shifts to lower temperatures with increasing h and correlates with the temperature dependence of the critical current. Furthermore, the ac susceptibility data can be analyzed by assuming that these granular materials are composed of a multiconnected Josephson network which behaves coherently as a single, weakly-connected superconducting loop.
KeywordsCritical Current Josephson Junction Thin Film Form Superconducting Oxide Meissner Effect
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