Magnetic-dipole induced appearance of vortices in a bilayered superconductor/soft-magnet heterostructure

TL;DR

This study investigates how a magnetic dipole influences vortex formation in a bilayer superconductor/soft-magnet structure, revealing that the soft-magnet layer can inhibit vortex penetration depending on the dipole's position.

Contribution

It provides analytical critical dipole moments for vortex and vortex-antivortex pair formation in a bilayer heterostructure, highlighting the soft-magnet's inhibitory effect.

Findings

Soft-magnet layer inhibits vortex penetration when facing the dipole.

Critical dipole moments depend on the dipole's position relative to the layers.

Vortex and vortex-antivortex pair formation thresholds are analytically determined.

Abstract

The penetration of the magnetic field of an infinitesimal magnetic dipole into a bilayered type-II superconductor/soft-magnet heterostructure is studied on the basis of the classical London approach. The critical values of the dipole moment for the first appearance of a single magnetic vortex and, respectively, a magnetic vortex-antivortex pair in the superconductor constituent are obtained, when the magnetic dipole faces the superconductor or the soft-magnet constituent. This reveals that the soft-magnet constituent inhibits penetration of vortices into the superconductor constituent, when the dipole faces the soft-magnet constituent.