Discovery of Weyl fermion semimetals and topological Fermi arc states

M. Zahid Hasan, Su Yang Xu, Ilya Belopolski, Shin Ming Huang

Research output: Contribution to journalReview articlepeer-review

291 Scopus citations


Weyl semimetals are conductors whose low-energy bulk excitations are Weyl fermions, whereas their surfaces possess metallic Fermi arc surface states. These Fermi arc surface states are protected by a topological invariant associated with the bulk electronic wave functions of the material. Recently, it has been shown that the TaAs and NbAs classes of materials harbor such a state of topological matter. We review the basic phenomena and experimental history of the discovery of the first Weyl semimetals, starting with the observation of topological Fermi arcs and Weyl nodes in TaAs and NbAs by angle and spin-resolved surface and bulk sensitive photoemission spectroscopy and continuing through magnetotransport measurements reporting the Adler-Bell-Jackiw chiral anomaly. We hope that this article provides a useful introduction to the theory of Weyl semimetals, a summary of recent experimental discoveries, and a guideline to future directions.

Original languageEnglish (US)
Pages (from-to)289-309
Number of pages21
JournalAnnual Review of Condensed Matter Physics
StatePublished - Mar 31 2017

All Science Journal Classification (ASJC) codes

  • General Materials Science
  • Condensed Matter Physics


  • Chern number
  • Quantum Hall effect
  • Topological insulator
  • Topological invariant
  • Topological phase of matter
  • Topological phase transition
  • Weyl materials


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