Microscopic Theory of Plasmons in Substrate-supported Borophene*

Two-dimensional boron, or borophene, is a metallic monolayer material which hosts
low-loss, high-confinement, visible light plasmons, with possible applications in
nanoplasmonic devices. In contrast with graphene, borophene cannot be exfoliated
and has been synthesized on a variety of metallic substrates. In this talk, we
present first-principles density functional theory calculations of the dielectric and
plasmonic properties of borophene grown on Ag(111). We systematically investigate
the linear response and the momentum-dependent polarizability of borophene as a
function of its proximity to the metallic substrate. Our calculations indicate that the
plasmons in borophene are damped by the substrate, which we explain via a simple
electrodynamic model of coupled polarizabilities between the monolayer and
substrate. Using this model, we predict the plasmonic properties of borophene on a
variety of substrates that minimize plasmon damping.