Influence of magnetic surface anisotropy on spin wave reflection from the edge of ferromagnetic film

TL;DR

This paper investigates how surface magnetic anisotropy affects spin wave reflection and lateral shifts at the edge of a ferromagnetic film, revealing a sensitive dependence on anisotropy and the role of demagnetizing fields in beam bending.

Contribution

It provides new insights into the influence of surface magnetic anisotropy on spin wave reflection and the Goos-Hanchen effect in ferromagnetic films through combined simulations and analytical methods.

Findings

Negative lateral shift observed in reflected spin waves.

Lateral shift is highly sensitive to surface magnetic anisotropy.

Demagnetizing fields cause graded refractive index and beam bending.

Abstract

We study propagation of the Gaussian beam of spin waves and its reflection from the edge of thin yttrium-iron-garnet film with in-plane magnetization perpendicular to this edge. We have performed micromagnetic simulations supported by analytical calculations to investigate influence of the surface magnetic anisotropy present at the film edge on the reflection, especially in the context of the Goos-Hanchen effect. We have shown the appearance of a negative lateral shift between reflected and incident spin wave beams' spots. This shift is particularly sensitive to the surface magnetic anisotropy value and is a result of the Goos-Hanchen shift which is sensitive to the magnitude of the anisotropy and of the bending of spin wave beam. We have demonstrated that the demagnetizing field provide graded increase of the refractive index for spin waves, which is responsible for the bending.