Issue
EPL
Volume 80, Number 1, October 2007
Article Number 17002
Number of page(s) 5
Section Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties
DOI http://dx.doi.org/10.1209/0295-5075/80/17002
Published online 05 September 2007
EPL, 80 (2007) 17002
DOI: 10.1209/0295-5075/80/17002

Deconfinement of vortices with continuously variable fractions of the unit flux quanta in two-gap superconductors

J. Goryo, S. Soma and H. Matsukawa

Department of Physics and Mathematics, Aoyama Gakuin University - 5-10-1, Fuchinobe, Sagamihara, 229-8558, Japan


received 21 June 2007; accepted in final form 9 August 2007; published October 2007
published online 5 September 2007

Abstract
We propose a new stage of confinement-deconfinement transition, which can be observed in laboratory. In two-gap superconductors (SCs), two kinds of vortex exist and each of them carries a continuously variable fraction of the unit flux quanta $\Phi _{0}$ = hc/2e. The confined state of these two is a usual vortex and stable in the low-temperature region of the system under a certain magnetic field above Hc1. We see an analogy to quarks in a charged pion. An entropy gain causes two fractional vortices to be deconfined above a certain temperature.

PACS
74.20.De - Phenomenological theories (two-fluid, Ginzburg-Landau, etc.).

© Europhysics Letters Association 2007