Observation of phonon structural features of a tunnel type in the characteristics of superconductor-(normal metal) point contacts with an excess current
Zakharov A. A., Tsetlin M. B.
Experiments with Tc-Ag point contacts show that when there is a pronounced mismatch of the Fermi velocities at an S-N boundary, even in the absence of an insulating barrier, the derivative current-voltage characteristics exhibit clearly defined phonon structural features due to the tunnel state density of the superconductor.