title: Spin Polarization and Texture of the Fermi Arcs in the Weyl Fermion Semimetal TaAs.
abstract: A Weyl semimetal is a new state of matter that hosts Weyl fermions as quasiparticle excitations. The Weyl fermions at zero energy correspond to points of bulk-band degeneracy, called Weyl nodes, which are separated in momentum space and are connected only through the crystal's boundary by an exotic Fermi arc surface state. We experimentally measure the spin polarization of the Fermi arcs in the first experimentally discovered Weyl semimetal TaAs. Our spin data, for the first time, reveal that the Fermi arcs' spin-polarization magnitude is as large as 80% and lies completely in the plane of the surface. Moreover, we demonstrate that the chirality of the Weyl nodes in TaAs cannot be inferred by the spin texture of the Fermi arcs. The observed nondegenerate property of the Fermi arcs is important for establishing its exact topological nature, which reveals that spins on the arc form a novel type of 2D matter. Additionally, the nearly full spin polarization we observed (∼80%) may be useful in spintronic applications.
authors.affiliation: Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 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, New Jersey 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, New Jersey 08544, USA.
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Sanchez
authors.affiliation: Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.|Condensed Matter and Magnet Science Group, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.|Department of Physics, University of Central Florida, Orlando, Florida 32816, USA.
authors.forename: Madhab
authors.initials: M
authors.lastname: Neupane
authors.affiliation: Centre for Advanced 2D Materials and Graphene Research Centre National University of Singapore, 6 Science Drive 2, 117546 Singapore.|Department of Physics, National University of Singapore, 2 Science Drive 3, 117542 Singapore.
authors.forename: Guoqing
authors.initials: G
authors.lastname: Chang
authors.affiliation: The Institute for Solid State Physics (ISSP), University of Tokyo, Kashiwa, Chiba 277-8581, Japan.
authors.forename: Koichiro
authors.initials: K
authors.lastname: Yaji
authors.affiliation: International Center for Quantum Materials, School of Physics, Peking University, Beijing, China.
authors.forename: Zhujun
authors.initials: Z
authors.lastname: Yuan
authors.affiliation: International Center for Quantum Materials, School of Physics, Peking University, Beijing, China.
authors.forename: Chenglong
authors.initials: C
authors.lastname: Zhang
authors.affiliation: The Institute for Solid State Physics (ISSP), University of Tokyo, Kashiwa, Chiba 277-8581, Japan.
authors.forename: Kenta
authors.initials: K
authors.lastname: Kuroda
authors.affiliation: Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.
authors.forename: Guang
authors.initials: G
authors.lastname: Bian
authors.affiliation: International Center for Quantum Materials, School of Physics, Peking University, Beijing, China.
authors.forename: Cheng
authors.initials: C
authors.lastname: Guo
authors.affiliation: International Center for Quantum Materials, School of Physics, Peking University, Beijing, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Lu
authors.affiliation: Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan.
authors.forename: Tay-Rong
authors.initials: TR
authors.lastname: Chang
authors.affiliation: Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 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, New Jersey 08544, USA.
authors.forename: Hao
authors.initials: H
authors.lastname: Zheng
authors.affiliation: Centre for Advanced 2D Materials and Graphene Research Centre National University of Singapore, 6 Science Drive 2, 117546 Singapore.|Department of Physics, National University of Singapore, 2 Science Drive 3, 117542 Singapore.
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, 117546 Singapore.|Department of Physics, National University of Singapore, 2 Science Drive 3, 117542 Singapore.
authors.forename: Shin-Ming
authors.initials: SM
authors.lastname: Huang
authors.affiliation: Centre for Advanced 2D Materials and Graphene Research Centre National University of Singapore, 6 Science Drive 2, 117546 Singapore.|Department of Physics, National University of Singapore, 2 Science Drive 3, 117542 Singapore.
authors.forename: Chuang-Han
authors.initials: CH
authors.lastname: Hsu
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, Northeastern University, Boston, Massachusetts 02115, USA.
authors.forename: Arun
authors.initials: A
authors.lastname: Bansil
authors.affiliation: Joseph Henry Laboratory, Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.
authors.forename: Titus
authors.initials: T
authors.lastname: Neupert
authors.affiliation: The Institute for Solid State Physics (ISSP), University of Tokyo, Kashiwa, Chiba 277-8581, Japan.
authors.forename: Fumio
authors.initials: F
authors.lastname: Komori
authors.affiliation: The Institute for Solid State Physics (ISSP), University of Tokyo, Kashiwa, Chiba 277-8581, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kondo
authors.affiliation: The Institute for Solid State Physics (ISSP), University of Tokyo, Kashiwa, Chiba 277-8581, Japan.
authors.forename: Shik
authors.initials: S
authors.lastname: Shin
authors.affiliation: Centre for Advanced 2D Materials and Graphene Research Centre National University of Singapore, 6 Science Drive 2, 117546 Singapore.|Department of Physics, National University of Singapore, 2 Science Drive 3, 117542 Singapore.
authors.forename: Hsin
authors.initials: H
authors.lastname: Lin
authors.affiliation: International Center for Quantum Materials, School of Physics, Peking University, Beijing, 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, New Jersey 08544, USA.
authors.forename: M Zahid
authors.initials: MZ
authors.lastname: Hasan