Study of phonon-injection-induced destruction of superconductivity in tin films

Abstract

We have investigated the phenomenon of the destruction of superconductivity in thin film strips of tin by injecting direct currents through a transverse normal metal (silver) strip in direct contact with the superconducting strip. We observe that the critical current of the superconducting tin strip decreases continuously (in some cases with an intermediate jump discontinuity) with increasing injection current. From a careful consideration of various possible mechanisms, such as current-induced depairing, simple heating, and nonequilibrium superconductivity, we infer that the experimental observations could be mostly due to steady-state nonequilibrium phenomena associated with heat pumping from various locally heated regions.