Snell's law for spin waves at a 90-degree domain wall

TL;DR

This paper experimentally demonstrates how magnetostatic spin waves refract and reflect at a 90-degree magnetic domain wall, revealing phenomena like negative refraction and confirming a Snell's law analogy for spin waves.

Contribution

It provides the first experimental observation of spin wave refraction and reflection at a 90-degree domain wall, including negative refraction, with a theoretical explanation based on dispersion relation rotation.

Findings

Observation of spin wave refraction and reflection at a 90-degree domain wall.

Identification of negative refraction of spin waves.

Validation of a Snell's law-like behavior for spin waves.

Abstract

We report experimental observation of the refraction and re ection of propagating magnetostatic spin waves crossing a 90-degree domain wall (DW) in terms of time-resolved magneto-optical imaging. Due to the magnetization rotation across the 90-degree DW, the dispersion relation of magnetostatic spin waves rotates by 90 degrees, which results in the change in the propagation dynamics of spin waves in both sides of the DW. We observe the refraction and re ection of magnetosatatc spin waves at the 90-degree DW, and reveal their characteristics, such as negative refraction. The incident-angle dependence of the refraction angle is explained by the wavenumber conservation along the DW, same as the case of Snell's law for light.