Dynamics of Vortex Shells in Mesoscopic Superconducting Corbino Disks

TL;DR

This paper investigates vortex shell dynamics in mesoscopic superconducting disks under external currents, revealing complex behaviors including shell rotation, structural transitions, and flux motion influenced by temperature and pinning effects.

Contribution

It introduces a detailed analysis of vortex shell dynamics in Corbino disks, highlighting non-monotonous critical currents and structural transitions similar to atomic phenomena.

Findings

Vortex shells exhibit rigid rotation at low currents.

Critical currents depend non-monotonously on magnetic field.

Thermally-activated flux motion explains observed vortex behaviors.

Abstract

In mesoscopic superconducting disks vortices form shell structures as recently observed in Nb disks. We study the dynamics of such vortices, driven by an external current I_0, in a Corbino setup. At very low I_0, the system exhibits rigid body rotation while at some critical current I_c,i vortex shells rotate separately with angular velocities omega_i. This critical current I_c,i has a remarkable non-monotonous dependence on the applied magnetic field which is due to a dynamically-induced structural transition with a rearrangement of vortices over the shells similar to the Coster-Kronig transition in hollow atoms. Thermally-activated externally-driven flux motion in a disk with pinning centers explains experimentally observed omega_i as a function of I_0 and T and the dynamically-induced melting transition.