Magnetization reversals in a disk-shaped small magnet with an interface

TL;DR

This paper investigates how a vortex core in a nanodisk with two different ferromagnetic materials can be flipped by the interface, causing spin wave emissions, using a simplified 2D model.

Contribution

It introduces a model for vortex core dynamics in a bi-material nanodisk and demonstrates interface-induced core flipping and associated spin wave bursts.

Findings

Vortex core can be flipped by the interface depending on magnetic coupling.

Core flipping results in burst-like spin wave emissions.

The model captures key features of vortex-interface interactions.

Abstract

We consider a nanodisk possessing two coupled materials with different ferromagnetic exchange constant. The common border line of the two media passes at the disk center dividing the system exactly in two similar half-disks. The vortex core motion crossing the interface is investigated with a simple description based on a two-dimensional model which mimics a very thin real material with such a line defect. The main result of this study is that, depending on the magnetic coupling which connects the media, the vortex core can be dramatically and repeatedly flipped from up to down and vice versa by the interface. This phenomenon produces burst-like emission of spin waves each time the switching process takes place.