1/f noise properties of swift heavy ion irradiated epitaxial thin films ofYBCO

Effect of 250 MeV Ag-107 ion irradiation induced columnar defects on the no ise properties of the YBCO superconductor in the normal and superconducting state have been investigated. Magnitude of the spectral density of the noi se is found to scale inversely with the frequency and exhibit a quadratic d ependence on the bias current confirming that the noise arises due to the r esistance fluctuations. The magnitude of S-v has been found to decrease wit h decrease in temperature and shows a noise peak in the transition region. The noise performance of these materials in the vicinity of the superconduc ting transition as well as in the normal state is found to improve by an or der of magnitude after irradiation with 250 MeV Ag-107 ions. The decrease i n the magnitude of 1/f noise peak is due the irradiation induced enhanced f lux pinning of the material which suppresses the flux motion induced noise in the vicinity of T-c.