Magnetic Vortex Core Dynamics in a Ferromagnetic Dot

TL;DR

This paper investigates the dynamic behavior of magnetic vortex cores in micron-sized Permalloy dots, revealing oscillation frequencies that match theoretical predictions based on the dots' aspect ratio.

Contribution

It provides direct imaging and analysis of vortex core oscillations in ferromagnetic dots, confirming theoretical models with experimental data.

Findings

Vortex cores oscillate on a 10-ns timescale after magnetic field removal.

Oscillation frequencies depend on the aspect ratio of the dots.

Experimental results agree with theoretical calculations.

Abstract

We report direct imaging by means of x-ray photoemission electron microscopy of the dynamics of magnetic vortices confined in micron-size circular Permalloy dots that are 30 nm thick. The vortex core positions oscillate on a 10-ns timescale in a self-induced magnetostatic potential well after the in-plane magnetic field is turned off. The measured oscillation frequencies as a function of the aspect ratio (thickness/radius) of the dots are in agreement with theoretical calculations presented for the same geometry.