Excitation and reception of magnetostatic surface spin waves in thin conducting ferromagnetic films by coplanar microwave antennas. Part I: Theory

TL;DR

This paper presents a comprehensive theoretical model for the excitation and detection of magnetostatic surface waves in thin ferromagnetic films using coplanar microwave antennas, accounting for various interface interactions and validating with experimental data.

Contribution

It introduces a self-consistent numerical model that includes effects like magnetic anisotropy and Dzyaloshinskii-Moriya interaction, advancing the understanding of spin wave coupling in conducting ferromagnetic films.

Findings

Model accurately predicts coupling impedances.

Frequency non-reciprocity observed without dispersion asymmetry.

Good agreement with experimental scattering parameters.

Abstract

A fully self-consistent model for the excitation and reception of magnetostatic surface waves in thin ferromagnetic films by a set of coplanar antennas was developed and implemented numerically. The model assumes that the ferromagnetic film is highly conducting and is interfaced with non-magnetic metallic films, but is also suitable for modeling magneto-insulating films. Perpendicular magnetic anisotropy and Dzyaloshinskii-Moriya interaction can be included at both interfaces of the ferromagnetic layer. The model calculates the coupling impedances between the different strips constituting the coplanar antennas. In some situations, this leads to a frequency non-reciprocity between counter-propagating waves even in the case of no asymmetry in the spin-wave dispersion relation. Several intermediate results of the model were checked numerically and the final output of the model, given as the scattering parameters, $S_{11}$, $S_{12}$, and $S_{21}$ of the antenna system, were in good agreement with previous experimental studies.