Helicons in Weyl semimetals

TL;DR

This paper develops a theoretical model for helicons in Weyl semimetals, revealing how their unique topological properties and Berry curvature effects significantly modify electromagnetic wave propagation compared to conventional metals.

Contribution

It introduces a novel theory incorporating Berry curvature corrections into the optical conductivity, highlighting the impact of axion terms on helicon and plasmon dispersion in Weyl semimetals.

Findings

Helicons in Weyl semimetals exhibit altered dispersion relations due to topological effects.

The axion term significantly modifies electromagnetic responses in these materials.

Berry curvature corrections are crucial for accurate modeling of wave propagation.

Abstract

Helicons are transverse electromagnetic waves propagating in three-dimensional (3D) electron systems subject to a static magnetic field. We present a theory of helicons propagating through a 3D Weyl semimetal. Our approach relies on the evaluation of the optical conductivity tensor from semiclassical Boltzmann transport theory, with the inclusion of certain Berry curvature corrections that have been neglected in the earlier literature (such as the one due to the orbital magnetic moment). We demonstrate that the axion term characterizing the electromagnetic response of Weyl semimetals dramatically alters the helicon dispersion with respect to that in nontopological metals. We also discuss axion-related anomalies that appear in the plasmon dispersion relation.