Temperature Dependent Magnetization Reversal Process on a Single Magnetic Vortex*

Magnetic vortices can be the ground state of certain ferromagnetic systems. They have been subject of study for the past decade because they are good candidates for a variety of applications. Magnetic vortices can be nucleated in micron and sub-micron sized soft ferromagnetic disks because geometry constraints. Previous studies have shown the important effect that pinning sites can have in the magnetization reversal process of an ensemble of disks and in the dynamics of single disks. Moreover, low temperature measurements of single disks showed thermal dependence of the nucleation and annihilation fields. However, a detailed study of domain wall motion at low temperatures in a single disk is missing.

In this work, we used electrical contacts on top of a disk to measure the change in resistance when an in-plane magnetic field is applied. We find that the nucleation and annihilation fields depend on temperature, with different thermal energy barriers for nucleation and annihilation, pinning and depinning affect the reversal process. Micromagnetic simulations are also performed to confirm the results.