Magnon scattering and transduction in Coulomb-coupled quantum Hall ferromagnets

TL;DR

This paper theoretically demonstrates Coulomb interaction effects in quantum Hall ferromagnets, showing magnons can scatter off point charges and skyrmions can transduce magnons between layers, enabling long-range magnonics.

Contribution

It introduces the novel concept of Coulomb-mediated magnon scattering and transduction in quantum Hall ferromagnets, expanding understanding of spin dynamics in these systems.

Findings

Magnons can scatter off point charges at a distance.

Skyrmions can act as transducers for magnons between layers.

Long-range spin drag effects can occur in bilayer QHFMs.

Abstract

The magnetization field of a quantum Hall ferromagnet (QHFM) can host a variety of spin textures, including skyrmions and magnons. When projected into the lowest Landau level with $\nu = 1$ filling, the topological (Pontryagin) charge density of the magnetization field is proportional to the electric charge density, allowing for long-range spin-spin interactions. Inspired by recent experimental developments that enable all-electrical generation and detection of magnons, in this work we theoretically demonstrate two phenomena that can occur due to Coulomb interactions that are unique to QHFMs: magnons can scatter off of point charges at a distance, and skyrmions can act as transmitters and receivers for magnons to be transduced between separate layers of a bilayer QHFM. The latter Coulomb-mediated spin drag effect occurs at arbitrary distance and could facilitate long-range magnonics, such as detection of spin waves for future experiments in 2D materials.