Chiral Electromagnetic Waves in Weyl Semimetal

TL;DR

This paper demonstrates that Weyl semimetals with broken time-reversal symmetry can support chiral electromagnetic waves, which are analogous to quantum Hall edge states for photons, due to their non-zero gyrotropy caused by Weyl node separation.

Contribution

It introduces the concept of chiral electromagnetic waves in Weyl semimetals and links their existence to the material's gyrotropy and Weyl node separation.

Findings

Chiral electromagnetic waves can propagate where gyrotropy changes sign.

Weyl semimetals can host photon analogs of quantum Hall edge states.

Abstract

We show that Weyl semimetals with broken time-reversal symmetry can host chiral electromag- netic waves. The magnetization that results in a momentum space separation of a pair of opposite chirality Weyl nodes is also responsible for the non-zero gyrotropy parameter in the system. It is then shown that a chiral electromagnetic wave can propagate in a region of space where the gyrotropy parameter changes sign. Such waves are analogs of quantum Hall edge states for photons.