Single vortices observed as they enter NbSe$_2$

TL;DR

This study visualizes individual vortices entering NbSe₂ superconductors, revealing their leap across the edge influenced by magnetic field and sample thickness, explained by geometrical barrier and pinning effects.

Contribution

It provides direct optical observation of vortex entry dynamics in NbSe₂, highlighting the role of geometrical barriers and pinning in vortex behavior.

Findings

Vortices leap across the edge near the superconductor boundary.

Leap distance decreases with increasing magnetic field.

Behavior explained by geometrical barrier and bulk pinning effects.

Abstract

We observe single vortices as they penetrate the edge of a superconductor using a high-sensitivity magneto-optical microscope. The vortices leap across a gap near the edge, a distance that decreases with increasing applied field and sample thickness. This behaviour can be explained by the combined effect of the geometrical barrier and bulk pinning.