Modification of three-magnon splitting in a flexed magnetic vortex

TL;DR

This study investigates how static in-plane magnetic fields modify three-magnon splitting in deformed magnetic vortices, revealing new localized modes with lower threshold power and potential for neuromorphic magnonic applications.

Contribution

It demonstrates that vortex deformation via in-plane magnetic fields significantly alters three-magnon splitting, introducing localized modes with lower power thresholds and expanding nonlinear magnon dynamics understanding.

Findings

Deformation leads to additional secondary modes localized near the vortex core.

Localized modes exhibit the same splitting rules but with lower threshold power.

Small static fields effectively control the nonlinear spectral response.

Abstract

We present an experimental and numerical study of three-magnon splitting in a micrometer-sized magnetic disk with the vortex state strongly deformed by static in-plane magnetic fields. Excited with a large enough power at frequency $f_\mathrm{RF}$, the primary radial magnon modes of a cylindrical magnetic vortex can decay into secondary azimuthal modes via spontaneous three-magnon splitting. This nonlinear process exhibits selection rules leading to well-defined and distinct frequencies $f_\mathrm{RF}/2\pm \Delta f$ of the secondary modes. Here, we demonstrate that three-magnon splitting in vortices can be significantly modified by deforming the magnetic vortex with in-plane magnetic fields, leading to a much richer three-magnon response. We find that, with increasing field, an additional class of secondary modes is excited which are localized to the highly-flexed regions adjacent to the displaced vortex core. While these modes satisfy the same selection rules of three-magnon splitting, they exhibit a much lower three-magnon threshold power compared to regular secondary modes of a centered vortex. The applied static magnetic fields are small ($\simeq$ 10 mT), providing an effective parameter to control the nonlinear spectral response of confined vortices. Our work expands the understanding of nonlinear magnon dynamics in vortices and advertises these for potential neuromorphic applications based on magnons.