Vortex Dynamics-Mediated Low-Field Magnetization Switching in an Exchange-Coupled System

TL;DR

This study demonstrates how vortex dynamics in an exchange-coupled bilayer system can induce low-field magnetization switching, offering a new pathway for ultralow-power spintronic device applications.

Contribution

It reveals a non-local mechanism where vortex dynamics trigger reversed-domain nucleation in an exchange-coupled system, enabling low-field switching.

Findings

Vortex dynamics induce energy accumulation in the soft magnetic layer.

Reversed-domain nucleation occurs at low magnetic fields due to vortex-induced energy.

The mechanism enables reduction of switching fields for spintronic devices.

Abstract

A magnetic vortex has attracted significant attention since it is a topologically stable magnetic structure in a soft magnetic nanodisk. Many studies have been devoted to understanding the nature of magnetic vortex in isolated systems. Here we show a new aspect of a magnetic vortex the dynamics of which strongly affects the magnetic structures of environment. We exploit a nanodot of an exchange-coupled bilayer with a soft magnetic Ni81Fe19 (permalloy; Py) having a magnetic vortex and a perpendicularly magnetized L10-FePt exhibiting a large switching field (Hsw). The vortex dynamics with azimuthal spin waves makes the excess energy accumulate in the Py, which triggers the reversed-domain nucleation in the L10-FePt at a low magnetic field. Our results shed light on the non-local mechanism of a reversed-domain nucleation, and provide with a route for efficient Hsw reduction that is needed for ultralow-power spintronic devices.