Three-dimensional Character of the Magnetization Dynamics in Magnetic Vortex Structures - Hybridization of Flexure Gyromodes with Spin Waves

TL;DR

This study uses micromagnetic simulations to analyze 3D spin-wave eigenmodes in Permalloy disks, revealing hybridization effects that influence mode frequencies and explain vortex-core reversal phenomena in thicker disks.

Contribution

It introduces a detailed 3D analysis of spin-wave modes in magnetic vortex structures, highlighting hybridization effects with gyromodes and their impact on mode behavior.

Findings

Hybridization of gyromodes and spin waves affects mode frequencies.

3D character is crucial for understanding vortex-core reversal.

Thickness-dependent mode behavior observed in simulations.

Abstract

Three-dimensional linear spin-wave eigenmodes of a Permalloy disk having finite thickness are studied by micromagnetic simulations based on the Landau-Lifshitz-Gilbert equation. The eigenmodes found in the simulations are interpreted as linear superpositions (hybridizations) of 'approximate' three-dimensional eigenmodes, which are the fundamental gyromode $G_0$, the spin-wave modes and the higher-order gyromodes $G_N$ (flexure modes), the thickness dependence of which is represented by perpendicular standing spin waves. This hybridization leads to new and surprising dependencies of the mode frequencies on the disk thickness. The three-dimensional character of the eigenmodes is essential to explain the recent experimental results on vortex-core reversal observed in relatively thick Permalloy disks.