Flux-trapping characterization for superconducting electronics using a cryogenic widefield N-$V$ diamond microscope

TL;DR

This paper introduces a cryogenic widefield NV-diamond magnetic microscope for rapid, high-resolution imaging of flux vortices in superconducting devices, aiding flux mitigation strategies.

Contribution

It presents a novel imaging tool capable of fast, micrometer-scale flux vortex visualization at cryogenic temperatures, improving flux trapping analysis in superconducting electronics.

Findings

Measured vortex expulsion fields in Nb thin films.

Identified a crossover in vortex expulsion behavior between 10 and 20 μm strip widths.

Scaling results align with theoretical models and suggest defect influence.

Abstract

Magnetic flux trapping is a significant hurdle limiting the reliability and scalability of superconducting electronics, yet tools for imaging flux vortices remain slow or insensitive. We present a cryogenic widefield NV-diamond magnetic microscope capable of rapid, micrometer-scale imaging of flux trapping in superconducting devices. Using this technique, we measure vortex expulsion fields in Nb thin films and patterned strips, revealing a crossover in expulsion behavior between $10$ and $20~\mu$m strip widths. The observed scaling agrees with theoretical models and suggests the influence of film defects on vortex expulsion dynamics. This instrument enables high-throughput magnetic characterization of superconducting materials and circuits, providing new insight for flux mitigation strategies in scalable superconducting electronics.