# Excess of topological defects induced by confinement in vortex nanocrystals

## TL;DR

This study directly images vortex positions in nanocrystals to understand how confinement increases topological defects, affecting the entropy jump at the vortex lattice transition.

## Contribution

It reveals how confinement induces a defect-rich edge region and introduces the healing-length as a key parameter in vortex nanocrystal structure.

## Key findings

- Defect density increases near edges with decreasing nanocrystal size.
- Vortex rows bend within the healing-length near edges.
- Positional order resembles Bragg-glass phase at the center.

## Abstract

We directly image individual vortex positions in nanocrystals in order to unveil the structural property that contributes to the depletion of the entropy-jump entailed at the first-order transition. On reducing the nanocrystal size the density of topological defects increases near the edges over a characteristic length. Within this "healing-length" distance from the sample edge vortex rows tend to bend while towards the center of the sample the positional order of the vortex structure is what is expected for the Bragg-glass phase. This suggests that the healing-length may be a key quantity to model the entropy-jump depletion in the first-order transition of extremely-layered vortex nanocrystals.