VOLTAGE NOISE OF YBA2CU3O7-DELTA FILMS IN THE VORTEX-LIQUID PHASE

The voltage noise of YBa2Cu3O7-delta films is measured in the resistiv e vortex-liquid phase which occurs above the vortex-glass transition i n high magnetic fields. The excess voltage-noise spectral density S-V is found to vanish critically at the vortex-glass transition temperatu re T-g according to S-V alpha(T - T-g)(x), with x = 1.8 +/- 0.3, and t o have a 1/f frequency dependence. A model is constructed on the basis of critical slowing down of the vortex dynamics. The model adequately accounts for the experiments, and suggests that x can be identified w ith the critical exponent nu of the vortex-glass correlation length.