Bridge in micron-sized Bi2Sr2CaCu2O8+y sample act as converging lens for vortices

TL;DR

This study demonstrates that a bridge structure in micron-sized Bi2Sr2CaCu2O8+y superconducting samples acts as a converging lens for vortices, revealing insights into vortex interactions and sample thickness effects.

Contribution

It provides direct imaging evidence of vortex focusing by a bridge structure and estimates the bridge's thickness, advancing understanding of vortex behavior in mesoscopic superconductors.

Findings

Bridge acts as a vortex converging lens

Estimated bridge thickness is less than 0.6 μm

Vortex properties are unaffected by 0.5 μm thickness variations

Abstract

We report on direct imaging of vortex matter nucleated in micron-sized Bi2Sr2CaCu2O8+y superconducting samples that incidentally present a bridge structure. We find that when nucleating vortices in a field-cooling condition the deck of the bridge acts as a converging lens for vortices. By means of Bitter decoration images allowing us to quantify the enhancement of vortex-vortex interaction energy per unit length in the deck of the bridge, we are able to estimate that the deck is thinner than 0.6\,$\mu$m. We show that the structural properties of vortex matter nucleated in micron-sized thin samples are not significantly affected by sample-thickness variations of the order of half a micron, an important information for type-II superconductors-based mesoscopic technological devices.