# Hybrid plasmon-magnon polaritons in graphene-antiferromagnet heterostructures

## TL;DR

This paper explores hybrid polariton modes in a graphene-antiferromagnet heterostructure, revealing new surface magnon-plasmon and plasmon-magnon polaritons with tunable properties and potential for advanced photonic-magnonic applications.

## Contribution

It introduces and analyzes two novel hybrid polariton modes in graphene-antiferromagnet heterostructures, demonstrating their unique dispersion characteristics and tunability.

## Key findings

- Discovery of a surface magnon-plasmon polariton with sign-changing group velocity.
- Identification of a surface plasmon-magnon polariton with anticrossing dispersion.
- Potential for new functionalities by combining photons, magnons, and plasmons.

## Abstract

We consider a hybrid structure formed by graphene and an insulating antiferromagnet, separated by a dielectric of thickness up to $d\simeq 500 \,nm$. When uncoupled, both graphene and the antiferromagnetic surface host their own polariton modes coupling the electromagnetic field with plasmons in the case of graphene, and with magnons in the case of the antiferromagnet. We show that the hybrid structure can host two new types of hybrid polariton modes. First, a surface magnon-plasmon polariton whose dispersion is radically changed by the carrier density of the graphene layer, including a change of sign in the group velocity. Second, a surface plasmon-magnon polariton formed as a linear superposition of graphene surface plasmon and the antiferromagnetic bare magnon. This polariton has a dispersion with two branches, formed by the anticrossing between the dispersive surface plasmon and the magnon. We discuss the potential these new modes have for combining photons, magnons, and plasmons to reach new functionalities.