Topological Graphene plasmons in a plasmonic realization of the Su-Schrieffer-Heeger Model

TL;DR

This paper demonstrates a graphene-based platform that emulates the Su-Schrieffer-Heeger model, showing topological plasmonic states with potential for robust, tunable mid-IR applications.

Contribution

It introduces a novel graphene hybrid system supporting topological plasmonic states characterized by Zak's phase, enabling direct experimental detection and device applications.

Findings

Observation of bulk-edge correspondence in graphene plasmonic bands

Detection of localized interface states at topological domain walls

Gate-tunable topological plasmonic resonances

Abstract

Graphene hybrids, made of thin insulators, graphene, and metals can support propagating acoustic plasmons (AGPs). The metal screening modifies the dispersion relation of usual graphene plasmons leading to slowly propagating plasmons, with record confinement of electromagnetic radiation. Here, we show that a graphene monolayer, covered by a thin dielectric material and an array of metallic nanorods can be used as a robust platform to emulate the Su-Schrieffer-Heeger model. We calculate the Zak's phase of the different plasmonic bands to characterise their topology. The system shows bulk-edge correspondence: strongly localized interface states are generated in the domain walls separating arrays in different topological phases. We find signatures of the nontrivial phase which can directly be probed by far-field mid-IR radiation, hence allowing a direct experimental confirmation of graphene topological plasmons. The robust field enhancement, highly localized nature of the interface states, and their gate-tuned frequencies expand the capabilities of AGP-based devices.