Imaging of current-induced superconducting-resistive transitions by scanning electron microscopy in laser-deposited superconducting thin films of Y1Ba2Cu3O7−x

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Abstract
We have investigated the transport current‐induced resistive transitions in predominantly c‐axis oriented crystalline Y1Ba2Cu3O7−x superconducting thin films with scanning electron microscopic (SEM) imaging and its correlation with dc current‐voltage (I‐V) measurements. We find that there is a nonlinear gradual transition region in the I‐V curves that is caused by macroscopic effects (current ‘‘crowding’’, substrate defects, film thickness variation, etc.) and by microscopic dissipation effects. At a high current there is an abrupt transition to the normal state in the I‐V curve due to Joule heating. The SEM mapping provides a direct image of the above effects and is useful for characterization and study of fundamental transport properties of high Tc thin films.