Regensburg 2016 – scientific programme

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DS: Fachverband Dünne Schichten

DS 6: Graphene: Theory
(Joint session of DS, DY, HL, MA, O and TT organized by HL)

DS 6.2: Talk

Monday, March 7, 2016, 09:45–10:00, H17

Plasmon signature in Dirac-Weyl liquids — •Johannes Hofmann — TCM Group, Cavendish Laboratory, University of Cambridge, UK

I shall discuss theoretically as a function of temperature the plasmon mode arising in three-dimensional Dirac liquids, i.e., systems with linear chiral relativistic single-particle dispersion, within the random phase approximation. It is found that whereas no plasmon mode exists in the intrinsic (undoped) system at zero temperature, there is a well-defined finite-temperature plasmon with superlinear temperature dependence, rendering the plasmon dispersion widely tunable with temperature. The plasmon dispersion contains a logarithmic correction due to the ultraviolet-logarithmic renormalization of the electron charge, manifesting a fundamental many-body interaction effect as in quantum electrodynamics. The plasmon dispersion of the extrinsic (doped) system displays a minimum at finite temperature before it crosses over to the superlinear intrinsic behavior at higher temperature, implying that the high-temperature plasmon is a universal feature of Dirac liquids irrespective of doping. This striking characteristic temperature dependence of intrinsic Dirac plasmons along with the logarithmic renormalization is a unique manifestation of the three-dimensional relativistic Dirac nature of quasiparticle excitations and serves as an experimentally observable signature of three-dimensional Dirac materials.