Fluctuations in a mesoscopic superconducting ring: resonant behavior of conductivity and specific heat in two mode critical regime

TL;DR

This paper investigates how critical fluctuations in a mesoscopic superconducting ring influence conductivity and specific heat, revealing resonant behaviors near half-integer flux quantum due to degeneracy of low-energy states.

Contribution

It provides a detailed analysis of fluctuation effects in a mesoscopic superconducting ring within the Ginzburg-Landau framework, highlighting resonant phenomena at specific magnetic flux values.

Findings

Resonant non-monotonic behavior of conductivity and specific heat near half flux quantum.

Degeneracy of low-energy eigenstates causes dramatic fluctuation effects.

Quantitative predictions of fluctuation-induced peaks in physical properties.

Abstract

The critical fluctuations in a mesoscopic superconducting ring are studied within the Ginzburg-Landau approach. The nonlocal conductivity as well as the specific heat are calculated as functions of the magnetic flux $\Phi$ through the ring. At $\Phi=\Phi_0/2$ two low-energy eigenstates become degenerate and near this point the behavior of fluctuations-dependent quantities change dramatically: both the zero Fourier component $\sigma_0$ of the fluctuation conductivity and the specific heat become non-monotonic functions of $|\Phi-\Phi_0/2|$ with rather special resonant structure.