Anomalous fluctuation regimes at the FFLO transition

TL;DR

This paper investigates the unique fluctuation behaviors near the FFLO transition in superconductors, providing theoretical predictions that could help experimentally identify the elusive FFLO state.

Contribution

It offers a theoretical analysis of Gaussian fluctuations at the FFLO transition, highlighting distinctive signatures in thermodynamic quantities for experimental detection.

Findings

Distinct fluctuation regimes near the FFLO transition

Unique critical exponents for the FFLO state

Potential experimental markers for FFLO identification

Abstract

Recently some experimental evidences have been obtained in favour of the existence of the inhomogeneous Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) superconducting state in heavy-fermion superconductor CeCoIn_{5} and organic superconductor -(BETS)_{2}FeCl_{4}. However the unambiguous identification of FFLO state remains very difficult. We present the theoretical studies of the Gaussian fluctuations near the tricritical point (where the FFLO modulation appears) and demonstrate that the behavior of the fluctuational specific heat, paraconductivity and diamagnetism is qualitatively different from the usual superconducting transition. Special values of the critical exponent and the crossovers between different fluctuational regimes may provide a unique test for the FFLO state appearance.