Plasmons and screening in a monolayer of MoS2

We investigate the dynamical dielectric function of a monolayer of molybdenum disulfide within the random phase approximation. While in graphene damping of plasmons is caused by interband transitions, due to the large direct band gap in monolayer MoS₂ collective charge excitations enter the intraband electron hole continuum similarly to the situation in two-dimensional electron and hole gases. Since there is no electron-hole symmetry in MoS₂, the plasmon energies in p- and n-doped samples clearly differ. The breaking of spin degeneracy caused by the large intrinsic spin-orbit interaction leads to a beating of Friedel oscillations for sufficiently large carrier concentrations, for holes as well as for electrons.