title: Enhanced screening in chemically functionalized graphene.
abstract: Resonant scatterers such as hydrogen adatoms can strongly enhance the low-energy density of states in graphene. Here, we study the impact of these impurities on electronic screening. We find a two-faced behavior: Kubo formula calculations reveal an increased dielectric function ε upon creation of midgap states but no metallic divergence of the static ε at small momentum transfer q→0. This bad metal behavior manifests also in the dynamic polarization function and can be directly measured by means of electron energy loss spectroscopy. A new length scale l(c) beyond which screening is suppressed emerges, which we identify with the Anderson localization length.
authors.affiliation: Radboud University of Nijmegen, Institute for Molecules and Materials, Nijmegen, The Netherlands. s.yuan@science.ru.nl
authors.forename: Shengjun
authors.initials: S
authors.lastname: Yuan
authors.forename: T O
authors.initials: TO
authors.lastname: Wehling
authors.forename: A I
authors.initials: AI
authors.lastname: Lichtenstein
authors.forename: M I
authors.initials: MI
authors.lastname: Katsnelson