Subharmonics of energy gap in superconducting channels under non-Josephson generation
Abstract
A subharmonic structure of the energy gap in a superconducting channel is experimentally detected on the first derivative of the I–V curve for voltages lower than 2Δ/e. The dependence of the variation of subharmonic features on temperature, power, and frequency of the external radiation leads to the conclusion that the phase slip center displays the properties of the SNS structure under high voltages. At certain temperatures, a dip appears against the background of the subharmonic peak, and this is followed by the initiation of a non-Josephson generations in the sample. Measurements of the external signal reflected from the sample over a wide frequency range reveal that, during the generation, an internal resonance exists in the film at the generation frequency.