Three-magnon scattering of spin wave on edge-localized mode in thin ferromagnetic film

TL;DR

This paper investigates three-magnon scattering at the edge of a thin ferromagnetic film, revealing how edge effects and wave interactions produce complex, angle-dependent spin wave phenomena confirmed by analytical and micromagnetic simulations.

Contribution

It introduces a new analytical theory for edge-localized three-magnon scattering, highlighting the impact of reduced symmetry and phase effects on wave interactions.

Findings

Stimulated splitting generates larger wave amplitudes than confluence.

Scattered wave intensity depends strongly on incidence angle and frequency.

The behavior is explained by multiple three-magnon processes involving incident and reflected waves.

Abstract

Three-wave scattering is a fascinating phenomenon with many applications in various technologies. Reducing the system symmetry greatly affects three-wave scattering, which, in this case, goes beyond the simple momentum conservation law. In this study, we examine three-magnon scattering at the edge of a thin ferromagnetic film, when a bulk spin wave interacts with an edge-localized propagating spin-wave upon the reflection. This creates new bulk spin waves at mixed frequencies by means of three-magnon confluence or stimulated splitting processes. Using our developed analytical theory, which has been confirmed by full micromagnetic simulations, we demonstrate that the amplitude of the wave generated in the stimulated splitting process is several times larger than that generated in the confluence process, primarily due to the lower group velocity. Furthermore, intensity of inelastically scattered waves exhibit a pronounced dependence on the incidence angle and frequency of the edge spin wave that goes beyond existing qualitative models. We show that the observed behaviors can only be explained by taking into account, that the scattered waves are created by several elementary three-magnon processes involving the incident and reflected waves. The complex nature of the scattered wave creation results in a strong sensitivity of its amplitude to the phase accumulation of spin waves upon reflection.