RESISTANCE NOISE AT THE SUPERCONDUCTING TRANSITION IN THICK-FILMS OF YBA2CU3O7-DELTA

Measurements of the power spectral density of the resistance noise were performed in thick films of YBa2Cu3O7−δ with broad superconducting transitions and in the frequency range from 0.1 Hz to 100Hz. The normalized power spectrum (Sv/V2) of the excess noise depends on frequency as 1/fα with α=1 over a wide range of temperature. We have also found that at the transition, the magnitude of this excess noise shows peaks at the same temperatures at which R−1 (dR/dT) has peaks and also very close to the temperature at which the sample reaches its R=0 state. Possible sources of noise responsible for these effects are proposed. © 1990, Elsevier Science Publishers B.V. (North-Holland). All rights reserved.