The noise power spectral density in thin epitaxial YBa ₂ Cu ₃ O _7−δ films

Abstract

We have studied the noise power spectral density S(f, T) in YBa 2 Cu 3 O 7-δ thin films. Measurements were performed for various magnetic field, up to 14 T, and in a large range of temperatures. We found that in thin films deposed by the laser ablation method on the surface (001) of SrTiO 3 substrate, the noise power spectral density S(f) exhibits a lorentzian shape behavior in the mixed state and that all the peaks of temperature dependent noise power spectral density S(T) at a determined frequency value were appeared in large game of the temperature. Our results suggested that the noise power spectral density under the applied magnetic field in the mixed state does not come from thermal fluctuation and that the flux motion remains the most probable origin of the noise.

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

“…This strength decomposes the vortex bundles into smaller ones and the measured noise decreases. In the thermally activated-deepening region, defined for the interval in which S(f) increases continuously with temperature, the power spectral density S(f) exhibits a 1/f α type behavoir [7], were α is a constant. …”