ABSTRACT
The layered silicene and germanene have stirred a lot of theoretical and experimental studies, mainly owing to the buckled structure, important spin-orbital interactions, the hexagonal symmetry, and the nanoscaled thickness, especially for the first two critical factors. The significant differences among monolayer silicene, germanene, and graphene in Coulomb excitations are worthy of a systematic investigation. Both monolayer silicene and germanene have buckled structures. The single-particle and collective excitations of monolayer silicene are chosen for a model study. Its dielectric function, being in the absence of external electric and magnetic fields, is similar to that of monolayer graphene, since electronic states are double degenerate for the spin degree of freedom. For monolayer silicene, the magnetoelectronic Coulomb excitations, which are in the presence of an applied electric field and a tunable Fermi level, are thoroughly investigated using suitable and delicate calculations. Monolayer silicene, germanene, and graphene quite differ from one another in certain geometric structures, electronic properties, and Coulomb excitations.
