Temperature dependent nucleation and annihilation of individual magnetic vortices

TL;DR

This study investigates how temperature influences the nucleation and annihilation of magnetic vortices in permalloy disks, revealing different mechanisms at low and high temperatures affecting magnetization reversal.

Contribution

It provides new insights into the temperature-dependent mechanisms of vortex nucleation and annihilation in magnetic disks, combining experimental magnetometry with analysis of thermal activation and saturation magnetization effects.

Findings

Nucleation field shows nonmonotonic temperature dependence.

Annihilation field decreases monotonically with temperature.

Different mechanisms dominate at low and high temperatures.

Abstract

We studied the temperature dependence of the magnetization reversal in individual submicron permalloy disks with micro-Hall and bend-resistance magnetometry. The nucleation field exhibits a nonmonotonic dependence with positive and negative slopes at low and high temperatures, respectively, while the annihilation field monotonically decreases with increasing temperature, but with distinctly different slopes at low and high temperatures. Our analysis suggests that at low temperatures vortex nucleation and annihilation proceeds via thermal activation over an energy barrier, while at high temperatures they are governed by a temperature dependence of the saturation magnetization.