2025/06/02 by Kapur, Rohan T., Kehayias, Pauli, Tolpygo, Sergey K. +12
#Applied Physics (physics.app-ph) #FOS: Physical sciences #Instrumentation and Detectors (physics.ins-det) #Quantum Physics (quant-ph) #Superconductivity (cond-mat.supr-con)
paper · doi:10.48550/arxiv.2506.01906
Magnetic flux trapping is a significant hurdle limiting 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, micron-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~μm 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.