One-dimensional plasmons confined in bilayer graphene p-n junctions
  Gapless spectrum of graphene allows easy spatial separation of electrons and holes with an external in-plane electric field. Guided collective plasmon modes can propagate along the separation line, whose amplitude decays with the distance to it. Their spectrum and direction of propagation can be controlled with the strength and direction of in-plane electric field. In case of a bilayer graphene additional control is possible by the perpendicular electric field that opens a gap in the band spectrum of electrons. We investigate guided plasmon spectra in bilayer p-n junctions using hydrodynamics of charged electron liquid. 
N. M. Hassan, V. V. Mkhitaryan, E. G. Mishchenko
cond-mat.mes-hall