Enhancing superconducting critical current by randomness

TL;DR

This paper demonstrates that random defect distributions in type-II superconductors outperform ordered arrays in increasing critical current, due to their variable local density of pinning sites which better hinder vortex motion.

Contribution

The study provides clear evidence that random pinscapes with variable local density improve critical current more effectively than ordered arrays, introducing a new perspective on vortex pinning strategies.

Findings

Random pinscapes outperform ordered arrays in critical current enhancement.

Variations in local-density-of-pinning-sites (LDOPS) mitigate vortex motion.

Conformal mapping further enhances critical current by enlarging LDOPS distribution.

Abstract

The key ingredient of high critical currents in a type-II superconductor is defect sites that 'pin' vortices. Contrary to earlier understanding on nano-patterned artificial pinning, here we show unequivocally the advantages of a random pinscape over an ordered array in a wide magnetic field range. We reveal that the better performance of a random pinscape is due to the variation of its local-density-of-pinning-sites (LDOPS), which mitigates the motion of vortices. This is confirmed by achieving even higher enhancement of the critical current through a conformally mapped random pinscape, where the distribution of the LDOPS is further enlarged. The demonstrated key role of LDOPS in enhancing superconducting critical currents gets at the heart of random versus commensurate pinning. Our findings highlight the importance of random pinscapes in enhancing the superconducting critical currents of applied superconductors.