BROADBAND NOISE ACROSS THE MODE-LOCKING FREEZING IN DRIVEN VORTEX MATTER

摘要

We report on the measurements of broadband voltage noise generated by the driven vortex matter in and just below the peak-effect regime of a thick amorphous MoxGe1-x film. We focus on a change in broadband noise as the system undergoes the mode-locking (ML) resonance (ML freezing), which occurs when the ac drive superimposed on the dc drive excites the lattice-oscillation modes collectively. Independent of the field studied, the noise spectrum at low frequencies f is of Lorentzian type, while it is f-independent at high f (but well below the ac-drive frequency). We find that the magnitude of noise at high f decreases in the ML resonance.