Plasmon Modes in Bilayer-Monolayer Graphene Heterostructures

We investigate the dispersion relation and damping of plasmon modes in a bilayer-monolayer graphene heterostructure with carrier densities nBLG and nMLG at zero temperature within the random-phase-approximation taking into account the nonhomogeneity of the dielectric background of the system. We derive analytical expressions for plasmon frequencies by using long wavelength expansion of response and bare Coulomb interaction functions. We show that the optical plasmon dispersion curve of the bilayer-monolayer system lies slightly below that of double-layer graphene (DLG) and the acoustic one lies much lower than that of DLG. We find that while decay rates of acoustic modes of the system and DLG are remarkably different, those of optical modes in both double-layer systems are similar. Except the damping rate of acoustic mode, the properties of plasmon excitations in the considered system depend remarkably on the interlayer distance, inhomogeneity of the background, density ratio nMLG/nBLG and spacer dielectric constant, especially at large wave-vectors.