Vortex pinning by meandering line defects in planar superconductors

TL;DR

This paper investigates how meandering line defects influence vortex pinning in planar superconductors, using analytical methods to understand the effects of defect trajectory variations and identifying a delocalization transition at a critical angle.

Contribution

It provides an analytical framework for vortex-defect interactions with curved defects, revealing the impact of defect trajectory changes on vortex pinning.

Findings

Delocalization transition occurs at a critical defect angle.

Divergence of trapping length near the transition.

Analytical mapping to a straight defect with external tilt.

Abstract

To better understand vortex pinning in thin superconducting slabs, we study the interaction of a single fluctuating vortex filament with a curved line defect in (1+1) dimensions. This problem is also relevant to the interaction of scratches with wandering step edges in vicinal surfaces. The equilibrium probability density for a fluctuating line attracted to a particular fixed defect trajectory is derived analytically by mapping the problem to a straight line defect in the presence of a space and time-varying external tilt field. The consequences of both rapid and slow changes in the frozen defect trajectory, as well as finite size effects are discussed. A sudden change in the defect direction leads to a delocalization transition, accompanied by a divergence in the trapping length, near a critical angle.