Europhys. Lett.
Volume 75, Number 2, July 2006
Page(s) 315 - 320
Section Condensed matter: electronic structure, electrical, magnetic, and optical properties
Published online 28 June 2006
Europhys. Lett., 75 (2), pp. 315-320 (2006)
DOI: 10.1209/epl/i2006-10112-y

Microscopic model for multiple flux transitions in mesoscopic superconducting loops

D. Y. Vodolazov1, 2, F. M. Peeters1, T. T. Hongisto3 and K. Yu. Arutyunov3

1  Departement Fysica, Universiteit Antwerpen - Groenenborgerlaan 171 B-2020 Antwerpen, Belgium
2  Institute for Physics of Microstructures, Russian Academy of Sciences 603950 Nizhny Novgorod, GSP-105, Russia
3  University of Jyväskylä, Department of Physics, Nano Science Centre PB 35, 40014 Jyväskylä, Finland

received 13 February 2006; accepted in final form 31 May 2006
published online 28 June 2006

A microscopic model is constructed which is able to describe multiple magnetic flux transitions as observed in recent ultra-low temperature tunnel experiments on an aluminum superconducting ring with normal-metal-insulator-superconductor junctions (Phys. Rev. B, 70 (2004) 064514). The unusual multiple flux quantum transitions are explained by the formation of metastable states with large vorticity. Essential in our description is the modification of the pairing potential and the superconducting density of states by a sub-critical value of the persistent current which modulates the measured tunnel current. We also speculate on the importance of the injected non-equilibrium quasiparticles on the stability of these metastable states.

74.78.Na - Mesoscopic and nanoscale systems.

© EDP Sciences 2006