Two-step flux penetration in layered antiferromagnetic superconductor

TL;DR

This paper investigates how magnetic domain formation along Josephson vortices in layered antiferromagnetic superconductors affects flux penetration, leading to a plateau in flux density and defining a new critical field.

Contribution

It introduces the concept of a second critical field for flux penetration caused by vortex domain formation in layered antiferromagnetic superconductors.

Findings

Formation of magnetic domains along vortices modifies surface energy barrier.

Flux penetration exhibits a plateau in flux density versus magnetic field.

The plateau's end defines the second critical field for flux entry.

Abstract

A layered antiferromagnetic superconductor in the mixed state may posses magnetic domains created along the Josephson vortices. This may happen when an external magnetic field is strong enough to flip over magnetic moments, lying in the phase core of the Josephson vortex, from their ground state configuration. The formation of the domain structure of the vortices modifies the surface energy barrier of the superconductor. During this process the entrance of the flux is stopped and a newly created state exhibits perfect shielding. Such behavior should be visible as a plateau on the dependence of flux density as a function of the external magnetic field. The end of the plateau determines the critical field, which we call the second critical field for flux penetration.