CONDUCTANCE NOISE IN YBCO THIN-FILMS

Experimental results on the low frequency conductance noise in YBaCuO thin films are presented. The films have been obtained by different fa brication methods (co-evaporation, DC magnetron sputtering and excimer laser deposition). Conductance noise from electron and Cooper-pair nu mber fluctuations, electron mobility fluctuations, percolation and tem perature fluctuations have been identified in the different samples. I n the temperature range where the sample behaves as a percolating netw ork, the noise is caused by the stochastic switching of weak finks bet ween their normal and superconducting states. This effect dominates in the low temperature part of the superconducting transition in high qu ality thin films provided temperature fluctuation induced noise is neg ligible.