Non-local Plasma Spectrum of Graphene Interacting with a Thick Conductor

TL;DR

This paper develops a self-consistent field theory to analyze the non-local plasmon spectrum of graphene interacting with a thick conductor, revealing new undamped plasmon modes and their dependence on graphene's gap and coupling.

Contribution

It introduces a comprehensive model for the non-local plasmon dispersion in graphene coupled to a conductor, including numerical calculations for undamped spectra and novel plasmon regions.

Findings

Identification of undamped plasmon modes in gapped graphene

Discovery of new plasmon excitations not present in free-standing graphene

Numerical characterization of plasmon spectra across wave numbers

Abstract

Self-consistent field theory is used to obtain the non-local plasmon dispersion relation of monolayer graphene which is Coulomb-coupled to a thick conductor. We calculate numerically the undamped plasmon excitation spectrum for arbitrary wave number. For gapped graphene, both the low-frequency (acoustic) and high frequency (surface) plasmons may lie within an undamped opening in the particle-hole region. Furthermore, we obtain plasmon excitations in a region of frequency-wave vector space which do not exist for free-standing gapped graphene.