Evidences of vortex curvature and anisotropic pinning in superconducting films by quantitative magneto-optics

TL;DR

This study uses quantitative magneto-optics to observe magnetic field line curvature and anisotropic vortex pinning in superconducting films, revealing how defects influence vortex behavior and current distribution.

Contribution

It introduces a method to measure local magnetic field and current density, demonstrating the impact of anisotropic pinning on vortex curvature in superconducting films.

Findings

Magnetic field line curvature observed at the superconductor surface.

Anisotropic vortex pinning affects vortex curvature and current density.

Columnar defects influence flux diffusion and vortex behavior.

Abstract

We present the experimental observation of magnetic field line curvature at the surface of a superconducting film by local quantitative magneto-optics. In addition to the knowledge of the full induction field at the superconductor surface yielding the quantitative observation of the flux line curvature, our analysis method allows also local value measurements of the electrical current density inside the sample. Thus, we study the interplay between the electrodynamic constraints dictated by the film geometry and the pinning properties of the superconductor. In particular, we investigate the anisotropic vortex-pinning, due to columnar defects introduced by heavy ion irradiation, as revealed in the local current density dependence on the vortex curvature during magnetic flux diffusion inside the superconducting film.