Symmetry content and spectral properties of charged collective excitations for graphene in strong magnetic fields

¹ Department of Physics and Centre for Scientific Computing, University of Warwick - Coventry CV4 7AL, UK, EU
² Department of Physics, California State University Bakersfield - Bakersfield, CA 93311, USA
³ General Physics Institute, Russian Academy of Sciences - Moscow 119991, Russia

^a A.M.Fischer@warwick.ac.uk

Received: 8 July 2010
Accepted: 14 October 2010

Abstract

We show that graphene in a strong magnetic field with partially filled Landau levels sustains charged collective excitations —bound states of a neutral magnetoplasmon and free particles. In the limit of low density of excess charges, these are bound three-particle complexes. Some of these states are optically bright and may be detected in spectroscopy experiments, providing a direct probe of electron-electron interactions in graphene. The charged excitations can be classified using the geometrical symmetries —non-commutative magnetic translations and generalized rotations— in addition to the dynamical SU₄ symmetry in graphene. From the SU₄ symmetry point of view, such excitations are analogous to bound states of two quarks and one antiquark with four flavors. We establish a flavor optical selection rule to identify the bright states for experimental studies.