CLASSICAL LIMIT OF MICROWAVE DETECTION IN ATOMIC-SIZED SUPERCONDUCTING CONTACTS

A mechanically controllable break junction is used to obtain atomic-si zed superconducting point contacts and vacuum-barrier tunnel junctions , which are studied under the influence of a microwave field. The junc tions show pronounced structure in the current-voltage characteristics , which differs from the well-known Shapiro steps and quasiparticle st eps. The effect of the microwave irradiation results in a potential mo dulation over the junction. The observed structure is explained within a classical description.