Oscillations of magnetization and conductivity in anisotropic Fulde-Ferrell-Larkin-Ovchinnikov superconductors

TL;DR

This paper investigates the fluctuational properties of FFLO superconductors, revealing oscillations in magnetization and anisotropic paraconductivity, with implications for understanding their normal state behavior.

Contribution

It provides the first detailed derivation of magnetization and conductivity fluctuations in FFLO superconductors, highlighting unique oscillatory and anisotropic effects.

Findings

Oscillations between diamagnetism and paramagnetism due to FFLO fluctuations

Strong anisotropy in paraconductivity near the FFLO transition

Fluctuation effects are well-described within Gaussian approximation

Abstract

We derive the fluctuational magnetization and the paraconductivity of Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) superconductors in their normal state. The FFLO superconducting fluctuations induce oscillations of the magnetization between diamagnetism and unusual paramagnetism which originates from the competition between paramagnetic and orbital effects. We also predict a strong anisotropy of the paraconductivity when the FFLO transition is approached in contrast with the case of a uniform BCS state. Finally building a Ginzburg-Levanyuk argument, we demonstrate that these fluctuation effects can be safely treated within the Gaussian approximation since the critical fluctuations are proeminent only within an experimentally inaccessible temperature interval.