Longitudinal plasmon excitations of a model Nodal Line Semimetal

Topological semimetals (TSM) are an increasingly studied group of symmetry protected topological phases of matter. They contain conduction and valence bands that cross each other in the Brillouin zone (BZ). This crossing cannot be eliminated by perturbation of the Hamiltonian without breaking crystalline or time-reversal symmetry. For 3D TSM, two bands may cross along a closed curve referred to as a nodal line. These TSM are referred to as topological nodal line semimetals (TNLSM). We have calculated the plasmon dispersion relation for a model 3D NLSM. We determined the polarization bubble which is then substituted into the temperature, wave number and frequency-dependent dielectric function in the random-phase approximation (RPA). The self-sustained plasma oscillations as well as their life times due to Landau damping by the single-particle excitations are determined for this model NLSM at T=0 K. The Friedel oscillations associated with impurity screening are also examined.