Dynamic Evolution of Flux Distributions in a Pulse-driven Superconductor by High-speed Magneto-optical Imaging

TL;DR

This paper uses high-speed magneto-optical imaging to study how magnetic flux distributions evolve dynamically in a superconductor, revealing the critical role of surface barriers in vortex behavior.

Contribution

It introduces a high-speed imaging method to observe flux dynamics in superconductors, highlighting the importance of surface barriers during vortex penetration and exclusion.

Findings

Surface barrier is crucial for vortex dynamics.

Flux distribution evolves dynamically under transport current.

High-speed imaging captures rapid flux changes.

Abstract

The accurate understanding of flux dynamics is essential for the design and operation of superconducting circuits. The time evolution of flux-density distribution in an NbN strip by the transport current was observed using high-speed magneto-optical microscopy. It was determined that even for the dynamic penetration and exclusion of vortices under the transport current, the surface barrier is essential. This feature is important for the correct understanding of the complex behavior of state-of-the-art superconducting devices.