title: Observation of Fermi arc surface states in a topological metal.
abstract: The topology of the electronic structure of a crystal is manifested in its surface states. Recently, a distinct topological state has been proposed in metals or semimetals whose spin-orbit band structure features three-dimensional Dirac quasiparticles. We used angle-resolved photoemission spectroscopy to experimentally observe a pair of spin-polarized Fermi arc surface states on the surface of the Dirac semimetal Na3Bi at its native chemical potential. Our systematic results collectively identify a topological phase in a gapless material. The observed Fermi arc surface states open research frontiers in fundamental physics and possibly in spintronics.
authors.affiliation: Joseph Henry Laboratory, 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: Joseph Henry Laboratory, Department of Physics, Princeton University, Princeton, NJ 08544, USA.
authors.forename: Chang
authors.initials: C
authors.lastname: Liu
authors.affiliation: Department of Chemistry, Princeton University, Princeton, NJ 08544, USA.
authors.forename: Satya K
authors.initials: SK
authors.lastname: Kushwaha
authors.affiliation: Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan.
authors.forename: Raman
authors.initials: R
authors.lastname: Sankar
authors.affiliation: Department of Chemistry, Princeton University, Princeton, NJ 08544, USA.
authors.forename: Jason W
authors.initials: JW
authors.lastname: Krizan
authors.affiliation: Joseph Henry Laboratory, Department of Physics, Princeton University, Princeton, NJ 08544, USA.
authors.forename: Ilya
authors.initials: I
authors.lastname: Belopolski
authors.affiliation: Joseph Henry Laboratory, Department of Physics, Princeton University, Princeton, NJ 08544, USA.
authors.forename: Madhab
authors.initials: M
authors.lastname: Neupane
authors.affiliation: Joseph Henry Laboratory, Department of Physics, Princeton University, Princeton, NJ 08544, USA.
authors.forename: Guang
authors.initials: G
authors.lastname: Bian
authors.affiliation: Joseph Henry Laboratory, Department of Physics, Princeton University, Princeton, NJ 08544, USA.
authors.forename: Nasser
authors.initials: N
authors.lastname: Alidoust
authors.affiliation: Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan.
authors.forename: Tay-Rong
authors.initials: TR
authors.lastname: Chang
authors.affiliation: Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan. Institute of Physics, Academia Sinica, Taipei 11529, Taiwan.
authors.forename: Horng-Tay
authors.initials: HT
authors.lastname: Jeng
authors.affiliation: Department of Physics, National Sun Yat-Sen University, Kaohsiung 804, Taiwan.
authors.forename: Cheng-Yi
authors.initials: CY
authors.lastname: Huang
authors.affiliation: Department of Physics, National Sun Yat-Sen University, Kaohsiung 804, Taiwan.
authors.forename: Wei-Feng
authors.initials: WF
authors.lastname: Tsai
authors.affiliation: Graphene Research Centre and Department of Physics, National University of Singapore 117542.
authors.forename: Hsin
authors.initials: H
authors.lastname: Lin
authors.affiliation: Joseph Henry Laboratory, Department of Physics, Princeton University, Princeton, NJ 08544, USA.
authors.forename: Pavel P
authors.initials: PP
authors.lastname: Shibayev
authors.affiliation: Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan. National Synchrotron Radiation Research Center, Taiwan.
authors.forename: Fang-Cheng
authors.initials: FC
authors.lastname: Chou
authors.affiliation: Department of Chemistry, Princeton University, Princeton, NJ 08544, USA.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Cava
authors.affiliation: Joseph Henry Laboratory, 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