The transport properties of quench condensed granular superconductors (Pb, Sn, and Pb-Ag films) are presented and analyzed. These systems exhibit transitions from insulating to superconducting behavior as a function of intergrain spacing. Superconductivity is characterized by broad transitions in which the resistance drops exponentially with reducing temperature. The slope of the log R versus T curves turns out to be universally dependent on the normal state film resistance for all measured granular systems. It does not depend on the material, critical temperature, geometry, or experimental setup. We discuss possible physical scenarios to explain these findings.
|Number of pages||4|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - 1 Aug 2002|