Regensburg 2016 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 24: Transport: Weyl Semimetals

TT 24.3: Talk

Tuesday, March 8, 2016, 10:15–10:30, H18

Anisotropic density fluctuations, plasmons, and Friedel oscillations in nodal line semimetal — •Jun Won Rhim¹ and Yong Baek Kim² — ¹Max-Planck Institute for the Physics of Complex Systems — ²Department of Physics and Center for Quantum Materials, University of Toronto, Toronto, Ontario M5S 1A7, Canada

Motivated by recent experimental efforts on three-dimensional semimetals, we investigate the static and dynamic density response of the nodal line semimetal by computing the polarizability for both undoped and doped cases. The nodal line semimetal in the absence of doping is characterized by a ring-shape zero energy contour in momentum space, which may be considered as a collection of Dirac points. In the doped case, the Fermi surface has a torus shape and two independent processes of the momentum transfer contribute to the singular features of the polarizability even though we only have a single Fermi surface. In the static limit, there exist two independent singularities in the second derivative of the static polarizability. This results in the highly anisotropic Friedel oscillations which show the angle-dependent algebraic power law and the beat phenomena in the oscillatory electron density near a charged impurity. Furthermore, the dynamical polarizability has two singular lines along ℏω = γ p and ℏω = γ p sinη, where η is the angle between the external momentum p^→ and the plane where the nodal ring lies. From the dynamical polarizability, we obtain the plasmon modes in the doped case, which show anisotropic dispersions and angle-dependent plasma frequencies.