Plexcitons: Dirac points and topological modes

TL;DR

This paper predicts the formation of Dirac points and topologically protected modes in plexcitons, arising from strong exciton-plasmon coupling, with potential applications in nanoscale energy control and exotic matter phases.

Contribution

It introduces a theoretical framework for realizing Dirac cones and topological edge states in plexcitonic systems involving organic layers and metallic films.

Findings

Prediction of Dirac cones in plexciton bandstructure

Proposal of topologically protected one-way modes

Potential for exploring exotic phases of matter

Abstract

Plexcitons are polaritonic modes that result from the strong coupling between excitons and plasmons. We consider plexcitons emerging from the interaction of excitons in an organic molecular layer with surface plasmons in a metallic film. We predict the emergence of Dirac cones in the two-dimensional bandstructure of plexcitons due to the inherent alignment of the excitonic transitions in the organic layer. These Dirac cones may open up in energy by simultaneously interfacing the metal with a magneto-optical layer and subjecting the whole system to a perpendicular magnetic field. The resulting energy gap becomes populated with topologically protected one-way modes which travel at the interface of this plexcitonic system. Our theoretical proposal suggests that plexcitons are a convenient and simple platform for the exploration of exotic phases of matter as well as of novel ways to direct energy flow at the nanoscale.