Tunable plasmon modes in doped AA-stacked bilayer graphene

We study plasmon modes in doped AA-stacked bilayer graphene (BLG) within the nearestneighbor tight-binding and the random phase approximation. We obtain closed analytical expressions for the polarizability function which are used to calculate the low-energy dispersion relations of and the numerical results for both acoustic and optical plasmon modes. Our results reveal the potential of AA-stacked BLG to be used as a tunable plasmonic device. In particular we find that the long-wavelength acoustic plasmon disperses as omega(+) approximate to root max(vertical bar mu vertical bar, t(1))q/kappa with a phase space which shrinks and vanishes as the chemical potential approaches the interlayer hopping energy, preventing the existence of long-lived acoustic plasmon. Furthermore, we show that AAstacked BLG support long-lived optical plasmon only when the condition (1 + g(s)g(v)e(2)t(1)d vertical bar mu vertical bar/xv(p)(2) vertical bar mu vertical bar/t(1) )(1/2) < vertical bar mu vertical bar/t(1) is satisfied, specially indicating Landau damping of the optical plasmon in undoped AA-staked BLG even at long-wavelength limit. We also find that the optical plasmon mode disperses as omega(-) approximate to Delta + Cq(2) with constants that can be tuned by tuning the chemical potential.

Automated summary

The study of plasmon modes in doped AA-stacked bilayer graphene reveals the potential of using it as a tunable plasmonic device. The long-wavelength acoustic plasmon's existence is hindered as the chemical potential approaches the interlayer hopping energy. Optimal long-lived optical plasmon in undoped AA-stacked BLG can be achieved by satisfying specific conditions.