Coherent effects in granular superconducting films
Abstract
Films composed of a large number of Nb or V granules combined with normal metals (Cr or Ag) and deposited on a fluorophlogopite substrate in such a way that a series of bridges (contacts) with variable thickness formed, were studied experimentally. Investigations with constant current in UHF fields showed that a coherent state is established in the system of contacts as a result of electromagnetic interaction via the intrinsic or external radiation. The nature of the interaction is studied as a function of the power and frequency of the radiation, temperature, and geometry of the specimens. An excess current was discovered on the return path of the I-V curve, whose presence is related to the intrinsic coherent radiation of the system of contacts, observable by the characteristic current steps in the I–V curve. The frequency and power of the radiation are estimated and the detecting properties of the system of contacts are determined.