Spin waves involved in three-magnon splitting in synthetic antiferromagnets

TL;DR

This paper investigates the three-magnon splitting process in synthetic antiferromagnet spin wave conduits, combining experimental and analytical methods to understand the involved spin wave modes and their implications for microwave signal processing.

Contribution

It provides a detailed analysis of the spin wave modes involved in three-magnon splitting in synthetic antiferromagnets, highlighting the mode confinement effects and splitting channels.

Findings

Low order optical spin waves can split into non-degenerate acoustic spin wave doublets.

Multiple splitting channels occur simultaneously in the process.

The mode confinement influences the rules of three-magnon splitting.

Abstract

An important nonlinear effect in magnonics is the 3-magnon splitting where a high frequency magnon splits into two magnons of lower frequencies. Here, we study the 3-magnon splitting in spin wave conduits made from synthetic antiferromagnets. By combining inductive excitation, inductive detection, Brillouin Light Scattering imaging of the spin waves and analytical modeling based on conservation laws, we elucidate the nature of the spin waves involved in this process. We show in particular that low order optical spin waves propagating along the conduit can split in doublets of non-degenerate acoustic spin waves that have a standing wave character in the confined direction and unsymmetrical wavevectors in the direction of the spin wave conduit. Generally, several splitting channels run in parallel. The rules governing the three-magnon splitting and its interplay with the mode confinement have consequences for the applications in non-linear microwave signal processing based on spin waves.