Spin-wave spectra in periodically surface-modulated ferromagnetic thin films

TL;DR

This paper provides a theoretical analysis of spin-wave spectra in periodically surface-modulated ferromagnetic thin films, revealing how geometry influences band-gaps and spin-wave profiles, with validation through simulations.

Contribution

It introduces a plane-wave method to analyze the dynamic response of modulated ferromagnetic films, highlighting the effects of magnetic charges on band-gap formation and width.

Findings

Band-gaps are broader due to static magnetic charges.

Geometry controls spin-wave modes and profiles.

Model shows excellent agreement with resonance simulations.

Abstract

This article presents theoretical results for the dynamic response of periodically surface-modulated ferromagnetic thin films. For such system, the role of the periodic dipolar field induced by the modulation is addressed by using the plane-wave method. By controlling the geometry of the modulated volumes within the film, the frequency modes and spatial profiles of spin waves can be manipulated. The angular dependence of the frequency band-gaps unveils the influence of both dynamic and static magnetic charges, which reside in the edges of the etching periodic zones, and it is stablished that band-gap widths created by static magnetic charges are broader than the one created by dynamic magnetic charges. To corroborate the validity of the model, the theoretical results are compared with ferromagnetic resonance simulations, where a very good agreement is achieved between both methods. The theoretical model allows for a detailed understanding of the physics underlying these kind of systems, thereby providing an outlook to potential applications associated with magnonic crystals-based devices.