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.
@article{arxiv.1412.7198,
title = {Non-local Plasma Spectrum of Graphene Interacting with a Thick Conductor},
author = {Godfrey Gumbs and Andrii Iurov and N. J. M. Horing},
journal= {arXiv preprint arXiv:1412.7198},
year = {2014}
}