Non-linear radial spinwave modes in thin magnetic disks

TL;DR

This study investigates non-linear radial spin-wave modes in magnetic nano-disks with vortex states, revealing amplitude-dependent frequency shifts, soliton formation, and vortex core switching, supported by experiments and simulations.

Contribution

It provides new insights into non-linear spin-wave dynamics and vortex core switching in magnetic nano-disks through combined experimental and micromagnetic simulation analysis.

Findings

Spin-wave resonance peaks deform and redshift with increased excitation amplitude.

High excitation leads to soliton formation and vortex core switching.

Experimental results are quantitatively supported by micromagnetic simulations.

Abstract

We present an experimental investigation of radial spin-wave modes in magnetic nano-disks with a vortex ground state. The spin-wave amplitude was measured using a frequency-resolved magneto optical network analyzer, allowing for high-resolution resonance curves to be recorded. It was found that with increasing excitation amplitude up to about 10 mT, the lowest-order mode behaves strongly non-linearly as the mode frequency redshifts and the resonance peak strongly deforms. This behavior was quantitatively reproduced by micromagnetic simulations. At higher excitation the spinwaves are transformed into a soliton by self-focusing, and collapse onto the vortex core, dispersing the energy in short-wavelength spinwaves. Additionally, this process can lead to switching of the vortex polarization through the injection of a Bloch point.