Analysis of the noise voltage in high‐T_c superconducting thin films

Abstract

We measured the noise spectral density S V variations of YBa 2 Cu 3 O 7-δ films in a large range of frequencies f 0.1-1000 Hz, temperature T and under the effect of a magnetic field up to 14 T. in order to clarify the origin of the noise observed in thin films deposed by the laser ablation method on the surface (001) of SrTiO 3 substrate, the noise power spectral density S(f,T) of the noise variations versus temperature and frequency is presented in Fig. 3 for H = 14 T parallel to the ab plane, I = 3 nA. We can observe from this result that the noise spectral density S V (T) shows a marked enhancement near T c the temperature superconducting transition. Our results suggested that the main source for the noise in the mixed state is the thermally activated vortex motion in the high-T c superconducting thin films.