Ab initio modelling of dielectric screening and plasmon resonances in extrinsic silicene

Propagation of surface waves in extrinsic silicene is scrutinized, using time dependent density functional theory in linear response regime. Collective charge density oscillations are predicted to occur at energies ranging from a few meV to some eV. These oscillations are analogous to the extrinsic plasmon modes of monolayer graphene, which are generated by two different types of charge carriers, i.e., Dirac electrons moving with distinct Fermi velocities. Our findings show how the striking plasmonic properties of silicene and monolayer graphene are independent on the chemistry of the group-IV element, buckling parameter, or hybridization state. These properties have the potential of being exploited for the design of next-generation nanodevices operating at THz frequencies.