Vortex dynamics in the presence of a line of submicron holes along a superconducting microbridge

TL;DR

This study investigates how a line of submicron holes affects vortex dynamics and dissipation in amorphous NbGe superconducting microbridges, revealing temperature-dependent effects on vortex pinning and motion.

Contribution

It demonstrates the contrasting effects of submicron holes on vortex pinning and dissipation at different temperatures in superconducting microbridges.

Findings

Holes act as effective pinning centers at low temperatures.

Dissipation is reduced well below Tc due to pinning.

Near Tc, dissipation is unexpectedly enhanced due to weakened pinning and vortex channeling.

Abstract

We measured and compared the electric field vs current density characteristics in the vortex state of two amorphous Nb0.7Ge0.3 microbridges, with and without a line of submicron holes patterned along the sample axis. The power dissipation in the perforated sample exhibits a crossover, being reduced at temperatures well below the superconducting transition temperature Tc and unexpectedly enhanced close to Tc. At low temperatures the holes are efficient artificial pinning centres and reduce the average vortex velocity. We argue that the dissipation enhancement close to Tc is a consequence of a combination of the weakened pinning by the holes and an inhomogeneous driving-current distribution in their vicinity, which results in an increased average vortex velocity as well as in a channeling of the vortex motion through the holes.