The coupling of plasmon in metal with a dipolar mode in a monolayer of MoS2 and WS2

This study addresses the influence of a semiconducting monolayer of molybdenum disulfide (MoS2) and tungsten disulfide (WS2) on the dielectric function of a supporting metal using the random phase approximation. The large direct band gap and polarizability in monolayer MoS(2 )and WS2 result in the interband dipolar mode, which couples to the energy comparable intraband optical plasmon mode of the metal in the long-wavelength limit. The dispersions of two hybridized modes as zeros of the effective dielectric function that incorporates the polarization properties of both the semiconducting monolayer and the underlying metal are obtained. It is shown that the coupled plasmon-dipolar modes are split and that they gain the properties of both bare modes. Finally, the spectral weights of the obtained coupled modes that can be found from the dispersing peaks in the energy-loss function are calculated.