Soliton pair dynamics in patterned ferromagnetic ellipses

TL;DR

This paper studies the dynamic behavior of vortex pairs in patterned ferromagnetic ellipses, revealing how core polarization influences their resonant translational modes through microwave reflection and simulations.

Contribution

It provides new insights into vortex pair dynamics and the role of core polarization, combining experimental microwave measurements with micromagnetic simulations.

Findings

Strong resonances correspond to translational modes of vortex pairs.

Core polarization affects vortex dynamics more than static interactions.

Dynamics are dominated by core polarization effects.

Abstract

Confinement alters the energy landscape of nanoscale magnets, leading to the appearance of unusual magnetic states, such as vortices, for example. Many basic questions concerning dynamical and interaction effects remain unanswered, and nanomagnets are convenient model systems for studying these fundamental physical phenomena. A single vortex in restricted geometry, also known as a non-localized soliton, possesses a characteristic translational excitation mode that corresponds to spiral-like motion of the vortex core around its equilibrium position. Here, we investigate, by a microwave reflection technique, the dynamics of magnetic soliton pairs confined in lithographically defined, ferromagnetic Permalloy ellipses. Through a comparison with micromagnetic simulations, the observed strong resonances in the subgigahertz frequency range can be assigned to the translational modes of vortex pairs with parallel or antiparallel core polarizations. Vortex polarizations play a negligible role in the static interaction between two vortices, but their effect dominates the dynamics.