Enhancing of the in-plane FFLO-state critical temperature in heterostructures by the orbital effect of the magnetic field

TL;DR

This paper demonstrates that in-plane FFLO-state heterostructures can experience an increase in critical temperature due to the orbital effect of a magnetic field, contrary to its usual suppressive role.

Contribution

It reveals that the orbital effect of magnetic fields can enhance the critical temperature in in-plane FFLO-state heterostructures, a novel insight for superconductivity research.

Findings

Orbital magnetic field can increase $T_c$ in FFLO states.

Enhancement observed in S/F and S/N bilayers.

Effect may apply to various in-plane FFLO heterostructures.

Abstract

It is well-known that the orbital effect of the magnetic field suppresses superconducting $T_c$. We show that for a system, which is in the Larkin-Ovchinnikov-Fulde-Ferrell (FFLO) state at zero external magnetic field, the orbital effect of an applied magnetic field can lead to the enhancement of the critical temperature higher than $T_c$ at zero field. We concentrate on two systems, where the in-plane FFLO-state was predicted recently. These are equilibrium S/F bilayers and S/N bilayers under nonequilibrium quasiparticle distribution. However, it is suggested that such an effect can take place for any plane superconducting heterostructure, which is in the in-plane FFLO-state (or is close enough to it) at zero applied field.