Magnetic Vortex Core Reversal by Excitation of Spin Waves

TL;DR

This paper demonstrates that high-frequency spin wave excitation can reversibly switch the vortex core in magnetic nanostructures, expanding understanding of vortex dynamics and potential spintronics applications.

Contribution

It introduces a novel vortex core reversal mechanism driven by high-frequency spin wave modes, supported by experimental and simulation evidence.

Findings

Unidirectional vortex core reversal via azimuthal spin wave modes

Reversal occurs at frequencies above 1 GHz

Modification of the critical velocity concept for switching

Abstract

Micron-sized magnetic platelets in the flux closed vortex state are characterized by an in-plane curling magnetization and a nanometer-sized perpendicularly magnetized vortex core. Having the simplest non-trivial configuration, these objects are of general interest to micromagnetics and may offer new routes for spintronics applications. Essential progress in the understanding of nonlinear vortex dynamics was achieved when low-field core toggling by excitation of the gyrotropic eigenmode at sub-GHz frequencies was established. At frequencies more than an order of magnitude higher vortex state structures possess spin wave eigenmodes arising from the magneto-static interaction. Here we demonstrate experimentally that the unidirectional vortex core reversal process also occurs when such azimuthal modes are excited. These results are confirmed by micromagnetic simulations which clearly show the selection rules for this novel reversal mechanism. Our analysis reveals that for spin wave excitation the concept of a critical velocity as the switching condition has to be modified.