Theory of fluctuations in a two-band superconductor

TL;DR

This paper develops a microscopic theory for fluctuations in two-band superconductors like MgB$_{2}$, extending the Ginzburg-Landau approach to accurately predict fluctuation-related properties.

Contribution

It introduces a generalized nonlocal two-band Ginzburg-Landau functional derived from microscopic theory, improving the description of fluctuation phenomena in such superconductors.

Findings

Derived the microscopic fluctuation propagator.

Built the nonlocal two-band Ginzburg-Landau functional.

Calculated fluctuation specific heat and conductivity.

Abstract

A theory of fluctuations in two-band superconductor MgB$_{2}$ is developed. Since the standard Ginzburg-Landau (GL) approach fails in description of its properties, we generalize it basing on the microscopic theory of a two-band superconductor. Calculating the microscopic fluctuation propagator, we build up the nonlocal two-band GL functional and the corresponding time-dependent GL equations. This allows us to calculate the main fluctuation observables such as fluctuation specific heat and conductivity.