A new technique (division of the film into very many small squares) allows the observation of supercooling and superheating of superconducting layers under both parallel and perpendicular fields. The possible existence of "edge" nucleation in thick films, analogous to surface nucleation for semiinfinite samples, is shown. The superconducting parameters determined for films extrapolate correctly to known bulk values. Critical thicknesses for passage from type I to type II behavior agree with theoretical predictions. Nonlocal corrections to the penetration depth allow one to explain deviations from the Gorkov-Goodman relation for bulk metals.
Supercooling fields of In films condensed at 295 and 77 K ha ve been studied. Each series of films defines a different bulk material, whose Ginzburg-Landau (GL) parameter can be obtained from the measured supercooling fields. These bulk metals satisfy the Gor' kov-Goodman relation between the GL parameter and resistivity. Furthermore, this relation is also satisfied by GL parameters of individual type Il films condensed at 77K, while other layers condensed at 295K show deviations ascribed to nonlocal effects. The importance of a careful study of transport properties of the films for a correct interpretation of experiments is stressed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.