Quantum interference in finite-size mesoscopic rings

TL;DR

This paper models how magnetic flux influences supercurrent interference in finite mesoscopic rings, revealing sinusoidal resistance variations due to current distribution changes caused by screening effects.

Contribution

It introduces a Ginzburg-Landau based model to analyze the impact of screening currents on supercurrent interference in finite-size mesoscopic rings.

Findings

Resistance varies sinusoidally with magnetic flux

Screening currents induce spatial ordering of supercurrents

Interference effects occur without quasiparticle density change

Abstract

The Ginzburg-Landau theory is used to model the order parameter of a finite-size mesoscopic ring to investigate the effects of the onset of screening currents on the transport of incoming ones. The magnetic flux breaks the symmetry of currents between input and output stubs by means of an induced spatial ordering upon diamagnetic and paramagnetic supercurrents circulating in the ring. The distribution of those screening currents drives the interference of incoming/outgoing supercurrents resulting into a sinusoidal variation of resistance as a function of the magnetic flux even if the density of quasiparticles is not modified by the external magnetic field.