Noise and Mode-Locking Resonance of Driven Vortices in Type-II Superconductors

摘要

Voltage noise generated by the driven vortices in and just below the peak-effect regime of a thick amorphous Mo_(x)Ge_(1-x) film is presented, focusing on a change in broadband noise as the system undergoes the mode-locking (ML) resonance. ML occurs when the ac drive superimposed on the dc drive excites the lattice-oscillation modes collectively. Except for the field near the melting field, the noise spectrum is frequency (f)-independent at high f. We find that for all the fields studied the magnitude of noise at high f decreases in the ML resonance.