Vortex-antivortex dynamics and field-polarity-dependent flux creep in hybrid superconductor/ferromagnet nanostructures

TL;DR

This paper investigates vortex-antivortex arrays in superconductor/ferromagnet nanostructures, revealing field-polarity-dependent flux creep and unique vortex dynamics influenced by ferromagnetic dot lattices.

Contribution

It demonstrates how ferromagnetic dot lattices induce vortex-antivortex arrays and influence flux creep behavior in superconducting films, a novel insight into hybrid nanostructure vortex dynamics.

Findings

Critical current shifts to nonzero applied field.

Distinct vortex motion regimes observed at zero field.

Flux creep is strongly dependent on field polarity.

Abstract

Vortex-antivortex arrays that are created in a type-II superconducting film by lattices of ferromagnetic dots with perpendicular anisotropy have been investigated. The highest critical current is shifted to a nonzero value of the applied field, and current-voltage characteristics show different regimes of vortex motion even in zero-applied field due to the presence of the vortex-antivortex arrays. Creep of interstitial vortices is observed at low driving forces. This flux creep is strongly field-polarity dependent.