A study of spatial distribution of critical currents in high-T c films by the laser scanning microscopy method

Using low-temperature laser-scanning microscopy we have visualized the current-induced superconductivity destruction process in thin films of high-Tc materials of different quality. The critical current is shown to be controlled by local inhomogeneities and defects of the film, which need to be taken into account when analyzing current–voltage curves. A method is suggested for measuring critical currents in multiconnected superconducting circuits.