Precise probing spin wave mode frequencies in the vortex state of circular magnetic dots

TL;DR

This study provides detailed measurements of spin wave mode frequencies in vortex-state circular magnetic dots, revealing deviations from predictions at higher aspect ratios and demonstrating the interaction between spin waves and vortex modes.

Contribution

The paper introduces a comprehensive experimental analysis of spin wave modes in vortex-state dots, highlighting deviations from existing models at larger aspect ratios and modeling mode splitting.

Findings

Frequency splitting of azimuthal modes observed.

Deviation from predicted frequency dependence at Beta > 0.05.

Interaction between spin waves and vortex gyrotropic mode explained.

Abstract

We report on detailed broadband ferromagnetic resonance measurements of azimuthal and radial spin wave excitations in circular Permalloy dots in the vortex ground state. Dots with aspect ratio (Beta =height over radius) varied from 0.03 to 0.1 were explored. We found that for Beta exceeding approximately 0.05, variation of the spin wave eigenfrequencies with Beta deviates from the predicted dependence. The frequency splitting of two lowest azimuthal modes was observed. The experimentally observed dependence of the frequency splitting on beta was reasonably well described by dynamic splitting model accounting the spin-waves and, vortex gyrotropic mode interaction.