Dielectric And Electronic Properties Of Three-Dimensional Luttinger Semimetals With A Quadratic Band Touching

Due to strong spin-orbit coupling, charge carriers in three-dimensionsal quadratic-band-touching Luttinger semimetals have nontrivial wave functions characterized by a pseudospin of 3/2. We compute the dielectric permittivity of such semimetals at finite doping, within the random phase approximation. Because of interband coupling, the dielectric screening shows a reduced plasma frequency and an increased spectral weight at small wave vectors compared to a regular quadratic band. This weakens the effective Coulomb potential, modifying the single-particle self-energy for which we present both analytical and numerical results. At a low carrier density, the quasiparticle properties of this model strongly deviate from that of a single quadratic band. We compare our findings with experimental results for alpha-Sn, HgSe, HgTe, YPtBi, and Pr2Ir2O7.