In-plane magnetic field anisotropy of the FFLO state in layered superconductors

TL;DR

This paper theoretically investigates how the FFLO state in layered superconductors affects in-plane magnetic field anisotropy, predicting unique angular dependencies that can identify FFLO modulation.

Contribution

It introduces a theoretical analysis of the orbital effect and FFLO modulation interplay, explaining experimental angular dependence of superconductivity onset in organic conductors.

Findings

In-plane critical field anisotropy changes at the FFLO transition.

Predicted angular dependence of superconducting onset temperature.

Suggests FFLO modulation as the origin of experimental observations.

Abstract

There are strong experimental evidences of the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state formation in layered organic superconductors in parallel magnetic field. We study theoretically the interplay between the orbital effect and the FFLO modulation in this case and demonstrate that the in-plane critical field anisotropy drastically changes at the transition to the FFLO state. The very peculiar angular dependence of the superconducting onset temperature which is predicted may serve for unambiguous identification of the FFLO modulation. The obtained results permit us to suggest the modulated phase stabilization as the origin of the magnetic-field angle dependence of the onset of superconductivity experimentally observed in (TMTSF)$_{2}$ClO$_{4}$ organic conductors.