Measurement of the current–voltage characteristics of point contacts makes it possible to study the properties of individual crystallites in a superconducting ceramic. The critical current density in the superconducting regions of the ceramic La1.8Sr0.2CuO4, with a size of the order of several tens of angströms, is found to attain values of 108 A/cm2, which are of the same order of magnitude as the pair-breaking current density, as evaluated from the formulas of the standard theory of superconductivity.

Topics
Superconductivity, Current-voltage characteristic, Point contacts, Cryogenics, Ceramics
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© 1988 American Institute of Physics.
1988
American Institute of Physics