Little-Parks oscillations near a persistent current loop

TL;DR

This paper studies how a persistent current loop affects Little-Parks oscillations in a mesoscopic superconducting cylinder, revealing two distinct regimes due to magnetic field inhomogeneity, with observable effects in current measurements.

Contribution

It introduces a detailed analysis of inhomogeneous magnetic field effects on Little-Parks oscillations in tall cylinders using Ginzburg-Landau theory.

Findings

Two distinct oscillatory regimes identified in tall cylinders.

Inhomogeneity causes different flux piercing at various heights.

Transition between regimes is observable in current measurements.

Abstract

We investigate the Little-Parks oscillations caused by a persistent current loop set on the top edge of a mesoscopic superconducting thin-walled cylinder with a finite height. For a short cylinder the Little-Parks oscillations are approximately the same ones as the standard effect, as there is only one magnetic flux piercing the cylinder. For a tall cylinder the inhomogeneity of the magnetic field makes different magnetic fluxes pierce the cylinder at distinct heights and we show here that this produces two distinct Little-Parks oscillatory regimes according to the persistent current loop. We show that these two regimes, and also the transition between them, are observable in current measurements done in the superconducting cylinder. The two regimes stem from different behavior along the height, as seen in the order parameter, numerically obtained from the Ginzburg-Landau theory through the finite element method