# Surface dynamics of rough magnetic films

## TL;DR

This paper investigates the surface dynamics of rough magnetic films, focusing on how surface disorder affects magnon transport and the generation of surface magnons under microwave excitation.

## Contribution

It provides a detailed calculation of surface magnon dephasing and transport lifetimes in thick magnetic films, highlighting the effects of surface roughness and disorder.

## Key findings

- Surface magnons are not protected against disorder despite their chirality.
- Transport is less affected by long-range disorder due to suppressed back scattering.
- Surface roughness can generate significant surface magnons under uniform microwave fields.

## Abstract

The chirality of Damon-Eshbach (DE) magnons affects the transport of energy and angular momentum at the surface of magnetic films and spheres. We calculate the surface-disorder-limited dephasing and transport lifetimes of surface modes of sufficiently thick high-quality magnetic films such as yttrium iron garnet. In spite of their chirality surface magnons are not protected, but interact strongly with smooth surface roughness. Nevertheless, for long-range disorder the transport is much less affected by the suppressed back scattering (vertex correction). Moreover, in the presence of roughness ferromagnetic resonance under a \textit{uniform} microwave field can gennerate a considerable amount of surface magnons.