Time Delays in the Superconducting Transition of Lead Films

Publisher Website
Google Scholar
Abstract
Strips of lead between 500 A and 1000 A thick, evaporated onto mica substrates, were driven from the superconducting into the normal state by rectangular current pulses of 0.4 μsec duration. For current amplitudes just above the threshold value, there was an apparent delay of up to 0.4 μsec before resistance began to appear in the strip. A plausible explanation is that a minute portion of the strip in the neighborhood of a flaw is driven normal almost instantaneously, and that the Joule heating of this normal region eventually causes thermal propagation of the interphase boundary. The delay is the time that must elapse before the temperature of the nucleus rises sufficiently to initiate the thermal spreading process. Similar results were obtained with lead-indium alloys, but in the case of tin the delay was less than the instrumental resolution. The relevance of these results to the interpretation of dc critical currents is discussed.

This publication has 1 reference indexed in Scilit: