Discovery of a new type of topological Weyl fermion semimetal state in MoxW1-xTe2

Ilya Belopolski; Daniel S Sanchez; Yukiaki Ishida; Xingchen Pan; Peng Yu; Su-Yang Xu; Guoqing Chang; Tay-Rong Chang; Hao Zheng; Nasser Alidoust; Guang Bian; Madhab Neupane; Shin-Ming Huang; Chi-Cheng Lee; You Song; Haijun Bu; Guanghou Wang; Shisheng Li; Goki Eda; Horng-Tay Jeng; Takeshi Kondo; Hsin Lin; Zheng Liu; Fengqi Song; Shik Shin; M Zahid Hasan

doi:10.1038/ncomms13643

Discovery of a new type of topological Weyl fermion semimetal state in Mo_xW_1-xTe₂

Nat Commun. 2016 Dec 5:7:13643. doi: 10.1038/ncomms13643.

Authors

Ilya Belopolski¹, Daniel S Sanchez¹, Yukiaki Ishida², Xingchen Pan³, Peng Yu⁴, Su-Yang Xu¹, Guoqing Chang^{5

6}, Tay-Rong Chang⁷, Hao Zheng¹, Nasser Alidoust¹, Guang Bian¹, Madhab Neupane⁸, Shin-Ming Huang^{5

6}, Chi-Cheng Lee^{5

6}, You Song⁹, Haijun Bu³, Guanghou Wang³, Shisheng Li^{5

6}, Goki Eda^{5

6

10}, Horng-Tay Jeng^{7

11}, Takeshi Kondo², Hsin Lin^{5

6}, Zheng Liu^{4

12

13}, Fengqi Song³, Shik Shin², M Zahid Hasan^{1

14}

Affiliations

¹ Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.
² The Institute for Solid State Physics (ISSP), University of Tokyo, Kashiwa-no-ha, Kashiwa, Chiba 277-8581, Japan.
³ National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and Department of Physics, Nanjing University, Nanjing, 210093, China.
⁴ Centre for Programmable Materials, School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798, Singapore.
⁵ Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore.
⁶ Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117546, Singapore.
⁷ Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan.
⁸ Department of Physics, University of Central Florida, Orlando, Florida 32816, USA.
⁹ State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China.
¹⁰ Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore.
¹¹ Institute of Physics, Academia Sinica, Taipei 11529, Taiwan.
¹² NOVITAS, Nanoelectronics Centre of Excellence, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798, Singapore.
¹³ CINTRA CNRS/NTU/THALES, UMI 3288, Research Techno Plaza, 50 Nanyang Drive, Border X Block, Level 6, Singapore 637553, Singapore.
¹⁴ Princeton Institute for Science and Technology of Materials, Princeton University, Princeton, New Jersey 08544, USA.

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 Mo_xW_1-xTe₂ are 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 Mo_xW_1-xTe₂ at 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 Mo_xW_1-xTe₂ is a Type II Weyl semimetal. We also find that certain Weyl points are at the Fermi level, making Mo_xW_1-xTe₂ a promising platform for transport and optics experiments on Weyl semimetals.

Publication types

Research Support, U.S. Gov't, Non-P.H.S.
Research Support, Non-U.S. Gov't