title: TOPOLOGICAL MATTER. Discovery of a Weyl fermion semimetal and topological Fermi arcs.
abstract: A Weyl semimetal is a new state of matter that hosts Weyl fermions as emergent quasiparticles and admits a topological classification that protects Fermi arc surface states on the boundary of a bulk sample. This unusual electronic structure has deep analogies with particle physics and leads to unique topological properties. We report the experimental discovery of a Weyl semimetal, tantalum arsenide (TaAs). Using photoemission spectroscopy, we directly observe Fermi arcs on the surface, as well as the Weyl fermion cones and Weyl nodes in the bulk of TaAs single crystals. We find that Fermi arcs terminate on the Weyl fermion nodes, consistent with their topological character. Our work opens the field for the experimental study of Weyl fermions in physics and materials science.
authors.affiliation: Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ 08544, USA. Princeton Center for Complex Materials, Princeton Institute for Science and Technology of Materials, Princeton University, Princeton, NJ 08544, USA.
authors.forename: Su-Yang
authors.initials: SY
authors.lastname: Xu
authors.affiliation: Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ 08544, USA.
authors.forename: Ilya
authors.initials: I
authors.lastname: Belopolski
authors.affiliation: Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ 08544, USA. Princeton Center for Complex Materials, Princeton Institute for Science and Technology of Materials, Princeton University, Princeton, NJ 08544, USA.
authors.forename: Nasser
authors.initials: N
authors.lastname: Alidoust
authors.affiliation: Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ 08544, USA. Condensed Matter and Magnet Science Group, Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
authors.forename: Madhab
authors.initials: M
authors.lastname: Neupane
authors.affiliation: Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ 08544, USA.
authors.forename: Guang
authors.initials: G
authors.lastname: Bian
authors.affiliation: International Center for Quantum Materials, School of Physics, Peking University, China.
authors.forename: Chenglong
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan.
authors.forename: Raman
authors.initials: R
authors.lastname: Sankar
authors.affiliation: Centre for Advanced 2D Materials and Graphene Research Centre National University of Singapore, 6 Science Drive 2, Singapore 117546. Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542.
authors.forename: Guoqing
authors.initials: G
authors.lastname: Chang
authors.affiliation: International Center for Quantum Materials, School of Physics, Peking University, China.
authors.forename: Zhujun
authors.initials: Z
authors.lastname: Yuan
authors.affiliation: Centre for Advanced 2D Materials and Graphene Research Centre National University of Singapore, 6 Science Drive 2, Singapore 117546. Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542.
authors.forename: Chi-Cheng
authors.initials: CC
authors.lastname: Lee
authors.affiliation: Centre for Advanced 2D Materials and Graphene Research Centre National University of Singapore, 6 Science Drive 2, Singapore 117546. Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542.
authors.forename: Shin-Ming
authors.initials: SM
authors.lastname: Huang
authors.affiliation: Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ 08544, USA.
authors.forename: Hao
authors.initials: H
authors.lastname: Zheng
authors.affiliation: Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.
authors.forename: Jie
authors.initials: J
authors.lastname: Ma
authors.affiliation: Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ 08544, USA.
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Sanchez
authors.affiliation: Centre for Advanced 2D Materials and Graphene Research Centre National University of Singapore, 6 Science Drive 2, Singapore 117546. Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542. Department of Physics, Northeastern University, Boston, MA 02115, USA.
authors.forename: BaoKai
authors.initials: B
authors.lastname: Wang
authors.affiliation: Department of Physics, Northeastern University, Boston, MA 02115, USA.
authors.forename: Arun
authors.initials: A
authors.lastname: Bansil
authors.affiliation: Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan.
authors.forename: Fangcheng
authors.initials: F
authors.lastname: Chou
authors.affiliation: Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ 08544, USA. Princeton Institute for Science and Technology of Materials, Princeton University, Princeton, NJ 08544, USA.
authors.forename: Pavel P
authors.initials: PP
authors.lastname: Shibayev
authors.affiliation: Centre for Advanced 2D Materials and Graphene Research Centre National University of Singapore, 6 Science Drive 2, Singapore 117546. Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542.
authors.forename: Hsin
authors.initials: H
authors.lastname: Lin
authors.affiliation: International Center for Quantum Materials, School of Physics, Peking University, China. Collaborative Innovation Center of Quantum Matter, Beijing, 100871, China.
authors.forename: Shuang
authors.initials: S
authors.lastname: Jia
authors.affiliation: Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ 08544, USA. Princeton Center for Complex Materials, Princeton Institute for Science and Technology of Materials, Princeton University, Princeton, NJ 08544, USA. mzhasan@princeton.edu.
authors.forename: M Zahid
authors.initials: MZ
authors.lastname: Hasan