Critical velocity for the vortex core reversal in perpendicular bias magnetic field

TL;DR

This study investigates how the critical velocity for vortex core reversal in magnetic nanodots varies with a perpendicular bias magnetic field, revealing size independence and a significant reduction near static reversal conditions.

Contribution

It introduces a detailed analysis of the dependence of critical vortex core reversal velocity on perpendicular bias magnetic fields, supported by an analytical model and numerical validation.

Findings

Critical velocity is independent of dot size.

Critical velocity decreases significantly near static reversal field.

Analytical model agrees well with numerical results.

Abstract

For a circular magnetic nanodot in a vortex ground state we study how the critical velocity $v_c$ of the vortex core reversal depends on the magnitude $H$ of a bias magnetic field applied perpendicularly to the dot plane. We find that, similarly to the case $H$ = 0, the critical velocity does not depend on the size of the dot. The critical velocity is dramatically reduced when the negative (i.e. opposite to the vortex core direction) bias field approaches the value, at which a \emph{static} core reversal takes place. A simple analytical model shows good agreement with our numerical result.