Critical current density in the superconducting ceramic $\mathrm{L}{\mathrm{a}}_{1.8}\mathrm{S}{\mathrm{r}}_{0.2}\mathrm{Cu}{\mathrm{O}}_4$ in S-c-N point contacts

Abstract

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 $\mathrm{L}{\mathrm{a}}_{1.8}\mathrm{S}{\mathrm{r}}_{0.2}\mathrm{Cu}{\mathrm{O}}_4$, with a size of the order of several tens of angstroms, is found to attain values of $10^{8}A/c{m}^2$, 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.

2 pages, 2 figures