HIGH-FREQUENCY RANDOM TELEGRAPH VOLTAGE NOISE IN HIGH-T-C THIN-FILMS

The vortex mechanism, leading to very high-frequency random telegraph voltage noise signals switching with MHz frequencies, is discussed. The mechanism assumes that vortices do not flow freely across dc-current-biased superconducting films but undergo subsequent processes of trapping and releasing from pinning centers. Random transitions of vortices between pinned and flow states result in the appearance of a Lorentzian component in a fluctuating-voltage power spectrum. It is shown that fluctuations of randomly distributed Abrikosov vortex density, rigidly moving across the strip, contribute an oscillating component to the noise spectrum. The distance between oscillating peaks corresponds to the time of flight of vortices across the strip. © 1994 The American Physical Society.