Electrodynamic response of type II Weyl semimetals

TL;DR

This study investigates the electrodynamic response of type II Weyl semimetals, specifically YbMnBi$_2$, using optical methods to identify unique spectral features and compare them with conventional semimetals, revealing new insights and challenges in understanding their behavior.

Contribution

The paper provides the first optical characterization of a type II Weyl semimetal, highlighting distinctive spectral signatures and challenging existing theoretical models.

Findings

Identification of optical fingerprints of type II Weyl fermions

Comparison reveals differences between type II Weyl and conventional semimetals

Results challenge current theoretical understanding of Weyl semimetal electrodynamics

Abstract

Weyl fermions play a major role in quantum field theory but have been quite elusive as fundamental particles. Materials based on quasi two-dimensional bismuth layers were recently designed and provide an arena for the study of the interplay between anisotropic Dirac fermions, magnetism and structural changes, allowing the formation of Weyl fermions in condensed matter. Here, we perform an optical investigation of YbMnBi$_2$, a representative type II Weyl semimetal, and contrast its excitation spectrum with the optical response of the more conventional semimetal EuMnBi$_2$. Our comparative study allows us disentangling the optical fingerprints of type II Weyl fermions, but also challenge the present theoretical understanding of their electrodynamic response.