Abstract:
Graphene, a two-dimensional form of carbon, has become famous for its wide range of unusual
properties, both fundamental and applicable. Both theory and experiment indicate the relevance
of many body interactions to the magneto-optical response of graphene. Neutral collective
excitations of pristine graphene in a strong perpendicular magnetic field have already been
studied theoretically. In this work, we consider graphene with a low impurity density and
determine the neutral magnetoplasmons, which become localised on an impurity. Two impurity
types are considered: a screened Coulomb impurity and a function scatterer due, e.g., to a
neutral foreign atom on one of the lattice sites. We assume Zeeman and valley splitting of
Landau levels (LLs) n=0 and «=±1, so that these LLs have four sublevels; we consider various
integer fillings of the zeroth LL. For both impurity types, we predict the existence of optically
active bound states above and below the magnetoplasmon continuum for high enough impurity
strengths (A. M. Fischer, A. B. Dzyubenko, and R. A. Romer, PRB 80, 165410 (2009)). Our results indicate
that polarisation-resolved magneto-optical spectroscopy can be an effective tool for
discriminating between different types of impurities in graphene.
