Pinning enhancement upon the magnetic flux trapping in the clusters of a normal phase with fractal boundaries

TL;DR

This paper investigates how fractal boundaries of normal phase clusters in type-II superconductors enhance magnetic flux pinning, leading to increased critical currents, with quantitative analysis of fractality effects.

Contribution

It introduces a model linking fractal boundary dimensions of normal phase clusters to improved flux pinning and critical current in superconductors.

Findings

Fractal boundaries increase flux pinning effectiveness.

Critical current is higher with more fractal boundary complexity.

Pinning gain coefficient depends on fractal dimension.

Abstract

The magnetic flux trapping in type-II superconductor containing fractal clusters of a normal phase, which act as pinning centers, is considered. The critical current distribution for an arbitrary fractal dimension of the boundaries of the normal phase clusters is obtained. It is revealed that the fractality of the cluster boundaries intensifies the pinning and thereby raises the critical current of a superconductor. The pinning gain coefficient as a function of critical current for different fractal dimensions is calculated.