Effective screening and the plasmaron bands in graphene

Electron-plasmon coupling in graphene has been shown recently to give rise to a "plasmaron" quasiparticle excitation. The strength of this coupling has been predicted to depend on the effective screening, which in turn is expected to depend on the dielectric environment of the graphene sheet. Here we compare the strength of environmental screening for graphene on four different substrates by evaluating the separation of the plasmaron bands from the hole bands using angle-resolved photoemission spectroscopy. Comparison with G₀W-random phase approximation predictions are used to determine the effective dielectric constant of the underlying substrate layer. We also show that plasmaron and electronic properties of graphene can be independently manipulated, an important aspect of a possible use in "plasmaronic" devices.