Vanishing Meissner effect as a hallmark of in-plane FFLO instability in superconductor - ferromagnet layered systems

TL;DR

This paper shows that the disappearance of the Meissner effect in layered superconductor-ferromagnet systems indicates the emergence of an in-plane FFLO superconducting phase, which is controllable by layer thickness and magnetization angles.

Contribution

It introduces the concept that the vanishing Meissner effect signals the in-plane FFLO phase in multilayered superconductor-ferromagnet systems, with controllable parameters and observable critical temperature oscillations.

Findings

Vanishing Meissner effect signals FFLO phase emergence.

FFLO instability occurs near critical temperature.

Critical temperature oscillates with magnetic field angle.

Abstract

We demonstrate that in a wide class of multilayered superconductor - ferromagnet structures (e.g., S/F, S/F/N and S/F/F') the vanishing Meissner effect signals the appearance of the in-plane Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) modulated superconducting phase. In contrast to the bulk superconductors the FFLO instability in these systems can emerge at temperatures close to the critical one and is effectively controlled by the S layer thickness and the angle between magnetization vectors in the F/F' bilayers. The predicted FFLO state reveals through the critical temperature oscillations vs the perpendicular magnetic field component.