Initial dissipation and current-voltage characteristics of superconductors containing fractal clusters of a normal phase

TL;DR

This paper studies how fractal clusters of a normal phase affect the initial dissipation and current-voltage behavior in type-II superconductors, revealing vortex depinning dynamics influenced by fractal structures.

Contribution

It provides experimental evidence linking fractal normal-phase clusters to vortex depinning and initial dissipation in superconductors, advancing understanding of flux dynamics.

Findings

Initial dissipation region observed near resistive transition

Vortex depinning influenced by fractal cluster structure

Broad current range indicates fractal nature of clusters

Abstract

The influence of fractal clusters of a normal phase on distinctive features of current-voltage characteristic of percolative type-II superconductors is considered. The results of high-resolution measurements of the differential resistance of BPSCCO/Ag composites are discussed in the context of magnetic flux dynamics. The region of initial dissipation is observed on current-voltage characteristics in the neighborhood of the transition into a resistive state. In the course of this stage of resistive transition the vortices start to break away from the normal-phase clusters, which act as pinning centers. The effect of transport current on vortex depinning is investigated. A broad current range of initial dissipation is considered as an evidence of fractal nature of the normal-phase clusters.