Zero-Index Weyl Metamaterials

Farzad Zangeneh-Nejad and Romain Fleury
Phys. Rev. Lett. 125, 054301 – Published 28 July 2020
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Abstract

Depending on the geometry of their Fermi surfaces, Weyl semimetals and their analogs in classical systems have been classified into two types. In type-I Weyl semimetals (WSMs), the conelike spectrum at the Weyl point is not tilted, leading to a pointlike closed Fermi surface. In type-II WSMs, on the contrary, the energy spectrum around the Weyl point is strongly tilted such that the Fermi surface transforms from a point into an open surface. Here, we demonstrate, both theoretically and experimentally, a new type of (classical) Weyl semimetal whose Fermi surface is neither a point nor a surface, but a flat line. The distinctive Fermi surfaces of such semimetals, dubbed as type-III or zero-index WSMs, gives rise to unique physical properties: one of the edge modes of the semimetal exhibits a zero index of refraction along a specific direction, in stark contrast to type-I and type-II WSMs for which the index of refraction is always nonzero. We show that the zero-index response of such topological phases enables exciting applications such as extraordinary wave transmission.

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  • Received 14 February 2020
  • Accepted 9 July 2020

DOI:https://doi.org/10.1103/PhysRevLett.125.054301

© 2020 American Physical Society

Physics Subject Headings (PhySH)

  1. Research Areas
Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Farzad Zangeneh-Nejad and Romain Fleury*

  • Laboratory of Wave Engineering, Swiss Federal Institute of Technology in Lausanne (EPFL), 1015 Lausanne, Switzerland

  • *Corresponding author. romain.fleury@epfl.ch

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Issue

Vol. 125, Iss. 5 — 31 July 2020

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