Probing vortices with a superconducting nanobridge

Abstract: 

We develop the electrical protocol allowing us to trap on demand the various superconducting vortex configurations in the field-cooled nanosquare, and test the trapped configurations by measuring the switching current of an adjacent Dayem nanobridge [1]. Our measurements exhibit unprecedented precision and ability to detect the first and successive vortex entries into all fabricated traps, from a few hundred nm to 2 μm in size.

Additionally, we perform experimental studies of hot electron diffusion in the presence of superconducting vortices. We obtain suppression of the diffusion signal due to the existence of a single vortex trapped in the box on the way between the source of hot electrons and the detecting nanobridge. In other words, we can see the single vortex by the influence it exerts on the flux of diffusing quasiparticles. For larger traps, holding many vortices, the effect is much more pronounced, but the signal at the detector does not vanish completely. Some energy reaches the bridge via the phonon emission channel, which is not affected by the magnetic field.

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.

 References:

 1. M.Foltyn, K.Norowski, M.J.Wyszyński, A.S. de Arruda, M.V.Milosevic, and M.Zgirski, Probing confined vortices with a superconducting nanobridge, Phys.Rev.Appl.(accepted, 2023)