Tunneling Density of States for a Superconductor Carrying a Current

Abstract

A current flowing in a superconducting film has a tendency to break pairs similar to the effect of paramagnetic impurities in a superconductor. The effect of the current on the tunneling density of states for a normal-superconducting tunneling junction has been computed by the Green's-function method of Abrikosov, Gorkov, and Maki, and found to be identical (for a short mean free path) to that of paramagnetic impurities. A simple relationship between the current parallel to the junction and the equivalent paramagnetic-impurity concentration is derived. Passing various amounts of current through the sample in the one experiment gives the same information as is obtainable in the other experiment only by preparing different samples with various impurity concentrations.