D-type Vortex and N-type Vortex in Two-gap Superconductor

TL;DR

This paper classifies two types of non-Abrikosov magnetic vortices in two-gap superconductors, revealing their topological properties and effects of Josephson interaction, expanding understanding of vortex structures beyond conventional models.

Contribution

It introduces D-type and N-type non-Abrikosov vortices with distinct core condensate behaviors and topologies, and analyzes the impact of Josephson interaction on these vortices.

Findings

D-type vortex has no condensate concentration at the core.

N-type vortex has a non-vanishing condensate at the core.

Vortices can carry fractional flux depending on parameters.

Abstract

We show that the two-gap superconductor has two types of non-Abrikosov magnetic vortex, the D-type which has no concentration of the condensate at the core and the N-type which has a non-vanishing concentration of the condensate at the core, which may carry $4\pi$-flux, $2\pi$-flux, or a fractional flux, depending on the parameters of the potential. Furthermore, we show that the non-Abrikosov vortex is described by two types of topology. The integer flux vortex has the non-Abelian topology $\pi_2(S^2)$, but the fractional flux vortex has the Abelian topology $\pi_1(S^1)$. We show that the inclusion of the Josephson interaction does not affect the existence of the magnetic vortex, but alter the shape of the vortex drastically.