Anomalous vortex dynamics in the low-temperature liquid phase of a thin a-MoxSi1−x film

We present measurements of the time(t)-dependent component of the flux-flow voltage δV(t) about the average voltage in the vortex-liquid phase of a thin amorphous MoxSi1−x film. At low temperatures T, δV(t) due to the vortex motion is clearly visible and the distribution of δV(t) is asymmetric, indicative of large velocity and/or number fluctuations of driven vortices. This result is very similar to that which has been observed in the quantum-liquid phase of a thick film. The anomalous vortex motion for the thick and thin films is found to occur in nearly the same reduced-temperature regime. Also, we find that for the thin film the anomalous motion is visible only in the high-field regime. We suggest that vortex dynamics in the low-T liquid phase of thin and thick films is dominated by common physical mechanisms related to quantum effects.