Anti-vortex dynamics in magnetic nanostripes

TL;DR

This paper investigates how out-of-plane magnetic fields influence anti-vortex nucleation and dynamics in magnetic nanostripes, revealing mechanisms to control domain wall speeds via micromagnetic simulations.

Contribution

It demonstrates that perpendicular magnetic fields inhibit anti-vortex formation, enabling faster domain wall motion, and elucidates the relationship between core size, crossing speed, and field alignment.

Findings

Out-of-plane fields suppress anti-vortex nucleation.

Aligned core moments affect anti-vortex crossing speed.

Perpendicular fields lead to asymmetrical anti-vortex motion.

Abstract

In a thin magnetic nanostripe, an anti-vortex nucleates inside a moving domain wall when driven by an in-plane magnetic field greater than the so-called Walker field. The nucleated anti-vortex must cross the width of the nanostripe before the domain wall can propagate again, leading to low average domain wall speeds. A large out-of-plane magnetic field, applied perpendicularly to the plane of the nanostripe, inhibits the nucleation of the anti-vortex leading to fast domain wall speeds for all in-plane driving fields. We present micromagnetic simulation results relating the anti-vortex dynamics to the strength of the out-of-plane field. An asymmetry in the motion is observed which depends on the alignment of the anti-vortex core magnetic moments to the direction of the out-of-plane field. The size of the core is directly related to its crossing speed, both depending on the strength of the perpendicular field and the alignment of the core moments and direction of the out-of-plane field.