Critical and non-critical coherence lengths in a two-band superconductor

TL;DR

This paper investigates the spatial coherence properties of a two-band superconductor, analyzing how intra- and interband interactions influence critical and non-critical coherence lengths and their temperature behaviors.

Contribution

It introduces a detailed analysis of coherence lengths in two-gap superconductors using Ginzburg-Landau equations derived from microscopic theory, highlighting the roles of intra- and interband couplings.

Findings

Identification of critical and non-critical coherence lengths.

Temperature dependence of coherence lengths varies with interaction contributions.

Analysis based on Ginzburg-Landau equations from Bogoliubov-de Gennes framework.

Abstract

We study the peculiarities of coherency in a two-gap superconductor. The both intraband couplings, inducing superconductivity in the independent bands, and interband pair-transfer interaction have been taken into account. On the basis of the Ginzburg-Landau equations derived from the Bogoliubov-de Gennes equations and the relevant self-consistency conditions for a two-gap system, we find critical and non-critical coherence lengths in the spatial behaviour of the fluctuations of order parameters. The character of the temperature dependencies of these length scales is determined by the relative contributions from intra- and interband interaction channels.