Wide-field magnetic imaging of shielding-current-driven vortex rearrangement under local heating using diamond quantum sensors

TL;DR

This study uses wide-field diamond NV sensors to image vortex behavior in NbN superconductors under local heating, revealing vortex rearrangement dynamics relevant for device applications.

Contribution

It demonstrates real-time, wide-field magnetic imaging of vortex rearrangement driven by local heating, advancing understanding of vortex dynamics in superconductors.

Findings

Vortex configurations change with local laser heating.

Rearrangement correlates with reduced pinning force and Lorentz force effects.

Real-time imaging captures vortex dynamics over 100 minutes.

Abstract

Understanding and controlling vortex motion in superconductors are important both for suppressing dissipation in superconducting devices and for device applications that exploit vortices. In this work, we quantitatively imaged the stray magnetic field distribution of vortices in an NbN thin film by wide-field magnetic imaging using a perfectly aligned diamond NV ensemble. By continuously measuring while stepwise varying the applied magnetic field under local laser heating, we captured a rearrangement of the vortex configuration in real space and in real time over more than 100 min. The observed vortex rearrangement is consistent with a reduction of the pinning force due to local laser heating and with the Lorentz force exerted by shielding currents induced by the field variation. These results provide insight into vortex dynamics and suggest potential applications, including vortex exclusion from sensitive regions of superconducting devices and vortex positioning in vortex-based devices.