Dynamic creation and annihilation of metastable vortex phase as a source of excess noise

The large increase in voltage noise, commonly observed in the vicinity of the peak-effect in superconductors, is ascribed to a novel noise mechanism. A strongly pinned metastable disordered vortex phase, which is randomly generated at the edges and annealed into ordered phase in the bulk, causes large fluctuations in the integrated critical current of the sample. The excess noise due to this dynamic admixture of two distinct phases is found to display pronounced re-entrant behavior. In the Corbino geometry the injection of the metastable phase is prevented and, accordingly, the excess noise disappears.