2000 character limit reached
Quasi-flat plasmonic bands in twisted bilayer graphene (1610.07757v1)
Published 25 Oct 2016 in cond-mat.mes-hall
Abstract: The charge susceptibility of twisted bilayer graphene is investigated in the Dirac cone, respectively random-phase approximation. For small enough twist angles $\theta\lesssim 2\circ$ we find weakly Landau damped interband plasmons, i.~e., collective excitonic modes which exist in the undoped material, with an almost constant energy dispersion. In this regime, the loss function can be described as a Fano resonance and we argue that these excitations arise from the interaction of quasi-localised states with the incident light field. These predictions can be tested by nano-infrared imaging and possible applications include a "perfect" lens without the need of left-handed materials.