GRAIN-SUPERCONDUCTIVITY EFFECT ON ELECTRICAL-CONDUCTION IN INSULATING GRANULAR FILMS

Abstract

We report the low-temperature conduction properties of indium/indium-oxide composite granular films in the insulating regime. The films show much stronger temperature dependence of resistance and large negative magnetoresistance below the superconducting transition temperature T(c) of the grains. The behavior is well explained by a grain-superconductivity effect.