title: Discovery of a new type of topological Weyl fermion semimetal state in MoxW1-xTe2.
abstract: The recent discovery of a Weyl semimetal in TaAs offers the first Weyl fermion observed in nature and dramatically broadens the classification of topological phases. However, in TaAs it has proven challenging to study the rich transport phenomena arising from emergent Weyl fermions. The series MoxW1-xTe2are inversion-breaking, layered, tunable semimetals already under study as a promising platform for new electronics and recently proposed to host Type II, or strongly Lorentz-violating, Weyl fermions. Here we report the discovery of a Weyl semimetal in MoxW1-xTe2at x=25%. We use pump-probe angle-resolved photoemission spectroscopy (pump-probe ARPES) to directly observe a topological Fermi arc above the Fermi level, demonstrating a Weyl semimetal. The excellent agreement with calculation suggests that MoxW1-xTe2is a Type II Weyl semimetal. We also find that certain Weyl points are at the Fermi level, making MoxW1-xTe2a promising platform for transport and optics experiments on Weyl semimetals.
authors.affiliation: Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.
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authors.affiliation: Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.
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authors.initials: DS
authors.lastname: Sanchez
authors.affiliation: The Institute for Solid State Physics (ISSP), University of Tokyo, Kashiwa-no-ha, Kashiwa, Chiba 277-8581, Japan.
authors.forename: Yukiaki
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authors.affiliation: National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and Department of Physics, Nanjing University, Nanjing, 210093, China.
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authors.affiliation: Centre for Programmable Materials, School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798, Singapore.
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authors.affiliation: Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.
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authors.affiliation: Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore.|Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117546, Singapore.
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authors.identifier: http://orcid.org/0000-0003-1180-3127
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authors.affiliation: Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan.
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authors.affiliation: Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.
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authors.identifier: http://orcid.org/0000-0002-6495-874X
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authors.affiliation: Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.
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authors.affiliation: Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.
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authors.affiliation: Department of Physics, University of Central Florida, Orlando, Florida 32816, USA.
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authors.affiliation: Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore.|Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117546, Singapore.
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authors.identifier: http://orcid.org/0000-0003-4273-9682
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authors.affiliation: Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore.|Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117546, Singapore.
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authors.initials: CC
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authors.affiliation: State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China.
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authors.affiliation: National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and Department of Physics, Nanjing University, Nanjing, 210093, China.
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authors.affiliation: National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and Department of Physics, Nanjing University, Nanjing, 210093, China.
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authors.affiliation: Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore.|Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117546, Singapore.
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authors.affiliation: Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore.|Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117546, Singapore.|Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore.
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authors.identifier: http://orcid.org/0000-0002-1575-8020
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authors.affiliation: Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan.|Institute of Physics, Academia Sinica, Taipei 11529, Taiwan.
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authors.affiliation: The Institute for Solid State Physics (ISSP), University of Tokyo, Kashiwa-no-ha, Kashiwa, Chiba 277-8581, Japan.
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authors.affiliation: Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore.|Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117546, Singapore.
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authors.affiliation: Centre for Programmable Materials, School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798, Singapore.|NOVITAS, Nanoelectronics Centre of Excellence, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798, Singapore.|CINTRA CNRS/NTU/THALES, UMI 3288, Research Techno Plaza, 50 Nanyang Drive, Border X Block, Level 6, Singapore 637553, Singapore.
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authors.affiliation: National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and Department of Physics, Nanjing University, Nanjing, 210093, China.
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authors.affiliation: The Institute for Solid State Physics (ISSP), University of Tokyo, Kashiwa-no-ha, Kashiwa, Chiba 277-8581, Japan.
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authors.affiliation: Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.|Princeton Institute for Science and Technology of Materials, Princeton University, Princeton, New Jersey 08544, USA.
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