Probing Confined Vortices with a Superconducting Nanobridge

We realize a superconducting nanodevice in which vortex traps in the form of an aluminum square are integrated with a Dayem nanobridge. We perform field cooling of the traps arriving to different vortex configurations, dependent on the applied magnetic field, to demonstrate that the switching current of the bridge is highly sensitive to the presence and location of vortices in the trap. Our measurements exhibit unprecedented precision and ability to detect the first and successive vortex entries into all fabricated traps, from few hundred nm to 2 mu m in size. The experimental results are corroborated by Ginzburg-Landau simulations, which reveal the subtle yet crucial changes in the density of the superconducting condensate in the vicinity of the bridge with every additional vortex entry and relocation inside the trap. An ease of integration and simplicity make our design a convenient platform for studying dynamics of vortices in strongly confining geometries, involving a promise to manipulate vortex states electronically with simultaneous in situ control and monitoring.

Automated summary

We demonstrate a superconducting nanodevice consisting of an aluminum square with integrated vortex traps and a Dayem nanobridge. By field cooling the traps, we show that the switching current of the bridge is highly sensitive to the presence and location of vortices. Our measurements accurately detect the first and successive vortex entries in traps ranging from few hundred nm to 2 μm in size, and the results are supported by simulations. This design provides a convenient platform for studying vortex dynamics in strongly confining geometries, with the potential for electronic manipulation and in situ control.