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 studying 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 , a representative type-II Weyl semimetal, and contrast its excitation spectrum with the optical response of the more conventional semimetal . Our comparative study allows us to disentangle the optical fingerprints of type-II Weyl fermions, but also challenges the present theoretical understanding of their electrodynamic response.
- Received 28 July 2016
- Revised 11 October 2016
DOI:https://doi.org/10.1103/PhysRevB.94.245101
©2016 American Physical Society