Critical-current fluctuations and flux-flow noise in type-II superconductors

By relying on a recent theory of transport in the mixed state and a related model of pinning in soft materials, the instantaneous critical current is introduced as a well-defined part ${\mathit{I}}_1$ of the total constant current. This nondissipative and time-dependent ${\mathit{I}}_1$ is assumed to be randomly distributed near the sample surface, and is described as a 2D turbulent homogeneous flow. Auto- and cross-correlation functions of both voltage and magnetic field noises are predicted and are in full agreement with experiments.