Vortex dynamics in the mixed state of amorphous MoxSi1-x films

We have performed the current-voltage and voltage-noise measurements for un iformly disordered thick amorphous MoxSi1-x films in various fields B. Belo w the melting field B-m where the depinning current I-C drops rapidly, the 1/f broad-band noise (BBN) is observed for I > I-C. Compared with the recen t simulation results, we find that the BBN originates from the plastic flow motion of vortices. We have also observed the large lif BBN at and near ze ro field, where its origin is different from the plastic flow motion. (C) 2 000 Elsevier Science B.V. All rights reserved.