Deconfinement of Vortices with Continuously Variable Fractions of the Unit Flux Quanta in Two-Gap Superconductors

TL;DR

This paper introduces a new confinement-decofinement transition in two-gap superconductors where vortices can carry continuously variable flux fractions, with deconfinement driven by entropy at higher temperatures.

Contribution

It proposes a novel transition mechanism in two-gap superconductors allowing vortices with variable flux fractions, analogous to quark confinement phenomena.

Findings

Vortices in two-gap SCs can carry continuous flux fractions.

A temperature-driven transition leads to vortex deconfinement.

The transition is analogous to quark deconfinement in particle physics.

Abstract

We propose a new stage of confiment-decofinment 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=h c / 2 e. 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 H_c1. We see an analogy to quarks in a charged pion. An entropy gain causes two fractional vortices to be deconfined above a certain temperature.