Multiple vortex-antivortex pair generation in magnetic nanodots

TL;DR

This paper investigates the formation of multiple vortex-antivortex pairs in magnetic nanodots driven by rotating magnetic fields, revealing complex nonlinear resonance phenomena and proposing experimental methods for their generation.

Contribution

It introduces a theoretical framework for understanding multidip structures with multiple vortex-antivortex pairs in nanodisks under dynamic magnetic fields.

Findings

Multidip structures can be generated with arbitrary vortex-antivortex pairs.

Nonlinear resonance of magnon modes underpins dip formation.

A proposed experimental setup for multidip structure creation.

Abstract

The interaction of a magnetic vortex with a rotating magnetic field causes the nucleation of a vortex--antivortex pair leading to a vortex polarity switching. The key point of this process is the creation of a dip, which can be interpreted as a nonlinear resonance in the system of certain magnon modes with nonlinear coupling. The usually observed single-dip structure is a particular case of a multidip structure. The dynamics of the structure with $n$ dips is described as the dynamics of nonlinearly coupled modes with azimuthal numbers $m=0,\pm n,\pm 2n$. The multidip structure with arbitrary number of vortex antivortex pairs can be obtained in vortex-state nanodisk using a space- and time-varying magnetic field. A scheme of a possible experimental setup for multidip structure generation is proposed.