Non-linear vortex dynamics and transient effects in ferromagnetic disks

TL;DR

This study investigates the complex non-linear relaxation dynamics of magnetic vortices in ferromagnetic disks using combined experimental imaging and micromagnetic simulations, revealing transient states and instabilities at large core displacements.

Contribution

It provides new insights into the non-linear vortex behavior and transient effects in patterned ferromagnetic disks under long field pulses.

Findings

Identification of vortex distortions beyond 20-25% core displacement

Observation of transient cross-tie wall states during relaxation

Detection of core polarization instabilities affecting vortex trajectories

Abstract

We report a time resolved imaging and micromagnetic simulation study of the relaxation dynamics of a magnetic vortex in the non-linear regime. We use time-resolved photoemission electron microscopy and micromagnetic calculations to examine the emergence of non-linear vortex dynamics in patterned Ni80Fe20 disks in the limit of long field pulses. We show for core shifts beyond ~20-25% of the disk radius, the initial motion is characterized by distortions of the vortex, a transient cross-tie wall state, and instabilities in the core polarization that influence the core trajectories.