title: Observation of Weyl nodes and Fermi arcs in tantalum phosphide.
abstract: A Weyl semimetal possesses spin-polarized band-crossings, called Weyl nodes, connected by topological surface arcs. The low-energy excitations near the crossing points behave the same as massless Weyl fermions, leading to exotic properties like chiral anomaly. To have the transport properties dominated by Weyl fermions, Weyl nodes need to locate nearly at the chemical potential and enclosed by pairs of individual Fermi surfaces with non-zero Fermi Chern numbers. Combining angle-resolved photoemission spectroscopy and first-principles calculation, here we show that TaP is a Weyl semimetal with only a single type of Weyl fermions, topologically distinguished from TaAs where two types of Weyl fermions contribute to the low-energy physical properties. The simple Weyl fermions in TaP are not only of fundamental interests but also of great potential for future applications. Fermi arcs on the Ta-terminated surface are observed, which appear in a different pattern from that on the As-termination in TaAs and NbAs.
authors.affiliation: Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen, Switzerland.|Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland.
authors.forename: N
authors.initials: N
authors.lastname: Xu
authors.affiliation: Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.|Collaborative Innovation Center of Quantum Matter, Beijing 10084, China.
authors.forename: H M
authors.initials: HM
authors.lastname: Weng
authors.affiliation: Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen, Switzerland.|Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: B Q
authors.initials: BQ
authors.lastname: Lv
authors.affiliation: Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen, Switzerland.
authors.forename: C E
authors.initials: CE
authors.lastname: Matt
authors.affiliation: Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen, Switzerland.
authors.forename: J
authors.initials: J
authors.lastname: Park
authors.affiliation: Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen, Switzerland.
authors.forename: F
authors.initials: F
authors.lastname: Bisti
authors.affiliation: Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen, Switzerland.
authors.forename: V N
authors.initials: VN
authors.lastname: Strocov
authors.affiliation: Laboratory for Developments and Methods, Paul Scherrer Institut, CH-5232 Villigen, Switzerland.
authors.forename: D
authors.initials: D
authors.lastname: Gawryluk
authors.affiliation: Laboratory for Developments and Methods, Paul Scherrer Institut, CH-5232 Villigen, Switzerland.
authors.forename: E
authors.initials: E
authors.lastname: Pomjakushina
authors.affiliation: Laboratory for Developments and Methods, Paul Scherrer Institut, CH-5232 Villigen, Switzerland.
authors.forename: K
authors.initials: K
authors.lastname: Conder
authors.affiliation: Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen, Switzerland.
authors.forename: N C
authors.initials: NC
authors.lastname: Plumb
authors.affiliation: Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen, Switzerland.
authors.forename: M
authors.initials: M
authors.lastname: Radovic
authors.affiliation: Institute of Theoretical Physics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland.|National Center for Computational Design and Discovery of Novel Materials MARVEL, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
authors.forename: G
authors.initials: G
authors.lastname: Autès
authors.affiliation: Institute of Theoretical Physics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland.|National Center for Computational Design and Discovery of Novel Materials MARVEL, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
authors.forename: O V
authors.initials: OV
authors.lastname: Yazyev
authors.affiliation: Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.|Collaborative Innovation Center of Quantum Matter, Beijing 10084, China.
authors.forename: Z
authors.initials: Z
authors.lastname: Fang
authors.affiliation: Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.|Collaborative Innovation Center of Quantum Matter, Beijing 10084, China.
authors.forename: X
authors.initials: X
authors.lastname: Dai
authors.affiliation: Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: T
authors.initials: T
authors.lastname: Qian
authors.affiliation: Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen, Switzerland.|Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland.|Laboratory for Solid State Physics, ETH Zürich, CH-8093 Zürich, Switzerland.
authors.forename: J
authors.initials: J
authors.lastname: Mesot
authors.affiliation: Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.|Collaborative Innovation Center of Quantum Matter, Beijing 10084, China.
authors.forename: H
authors.initials: H
authors.lastname: Ding
authors.affiliation: Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen, Switzerland.
authors.forename: M
authors.initials: M
authors.lastname: Shi