Plasmons of graphene and monolayer transition metal dichalcogenides double-layer

We investigate the plasmonic properties of a double-layer structure consisting of graphene and monolayer transition metal dichalcogenides (ML-TMDs) separated by a space distance $d$ where the carrier densities in different layers are $n_1$ and $n_2$ within the usual standard random-phase approximation (RPA) dielectric function approach. There exists two branches of plasmons for an acoustical mode and an optical mode, respectively. We examine the effect of carrier density, inter-layer spacing, and types of TMDs materials on the plasmon properties. Meanwhile, the two branches of plasmons have nonzero decay rates after entering the Landau damping regions for intra-band and inter-band single-particle excitation (SPE) continuum. The plasmons in double-layer structure exhibit significant tunability, offering promising applications of 2D materials for plasmonic devices.