Speed of the Superconducting-Normal Transition in Tin Films

WE have carried out some experiments to study the rate at which resistance is restored in a superconducting tin film by the application of a magnetic field above the critical value. No direct experiment of this kind has previously been reported, although Woodford and Feucht 1 , using a radiofrequency method, inferred that the transition in an evaporated film of an unspecified metal probably occurred in less than 10 −9 sec. The question is of some importance both from a fundamental point of view and in determining the lower limit of the switching time of superconducting circuit devices such as the cryotron.