# Unidirectional plasmonic edge modes on general two-dimensional materials

## TL;DR

This paper explores the directional control of edge plasmons in 2D materials through polarization and dipole positioning, extending theoretical models to anisotropic and hyperbolic systems, and validating findings with simulations.

## Contribution

It introduces a comprehensive analysis of unidirectional edge plasmon modes in general 2D materials, including anisotropic and hyperbolic systems, with validation against exact solutions.

## Key findings

- Identification of conditions for unidirectional edge plasmons.
- Extension of existing models to anisotropic and hyperbolic materials.
- Validation of theoretical predictions with simulations.

## Abstract

We investigate the field and spin-momentum coupling of edge plasmons hosted by general two-dimensional materials and identify sweet spots depending on the polarisation plane, ellipticity and the position of an electric dipole relative to the plane and edge. Exciting the dipole at these sweet spots by propagating light leads to uni-directional propagating edge plasmons or edge modes are totally suppressed. We also extent previous approximate treatments [A. Fetter Phys. Rev. B 32, 7676 (1985)] to include anisotropy and hyperbolic systems, elucidating its predictions for the existence of edge modes. A thorough assessment of the approximate description is carried out, comparing its spin-momentum coupling features in the near field with exact results from Wiener-Hopf techniques. Simulations are also performed confirming the overall picture. Our results shed new light on the quest of chiral plasmonics in 2D materials and should be relevant for future experiments.