Extreme anisotropy and gyrotropy of surface polaritons in Weyl semimetals

TL;DR

This paper investigates the unique electrodynamic properties of Weyl semimetals, focusing on surface polaritons, anisotropy, and gyrotropy, and explores optical spectroscopy techniques to probe their topological electron states.

Contribution

It introduces the potential of tip-enhanced optical spectroscopy to study surface and bulk states in Weyl semimetals, highlighting their extreme anisotropy and gyrotropy effects.

Findings

Surface polaritons exhibit anomalous dispersion and optical Hall effect.

Optical techniques can reveal Weyl node positions and Fermi momentum.

Surface and bulk electron states can be characterized through optical transitions.

Abstract

Weyl semimetals possess unique electrodynamic properties due to a combination of strongly anisotropic and gyrotropic bulk conductivity, surface conductivity, and surface dipole layer. We explore the potential of popular tip-enhanced optical spectroscopy techniques for studies of bulk and surface topological electron states in these materials. Anomalous dispersion, extreme anisotropy, and the optical Hall effect for surface polaritons launched by a nanotip provides information about Weyl node position and separation in the Brillouin zone, the value of the Fermi momentum, and the matrix elements of the optical transitions involving both bulk and surface electron states.