LOW-FREQUENCY VOLTAGE NOISE IN CURRENT BIASED HTCS THIN-FILMS

Pronounced changes in low-frequency noise power spectra have been observed, close to the transition temperature, in current biased high-T(c) superconducting thin films. Generally, the spectra scale as 1/f(alpha), where 0.5 < alpha < 2 and depends strongly on temperature and dc current flow. We attribute most of the changes in a to the activation of Random Telegraph Signals due to flux hopping processes. However, peaks of excess noise that show out at certain current flows can not be explained by the action of elementary two-level fluctuators, clearly indicating yet another mechanism contributing to the 1/f power spectra.