Title: A strongly robust type II Weyl fermion semimetal state in Ta₃S₂

Abstract

Weyl semimetals are of great interest because they provide the first realization of the Weyl fermion, exhibit exotic quantum anomalies, and host Fermi arc surface states. The separation between Weyl nodes of opposite chirality gives a measure of the robustness of the Weyl semimetal state. To exploit the novel phenomena that arise from Weyl fermions in applications, it is crucially important to find robust separated Weyl nodes. Here, we propose a methodology to design robust Weyl semimetals with well-separated Weyl nodes. Using this methodology as a guideline, we search among the material parameter space and identify by far the most robust and ideal Weyl semimetal candidate in the single-crystalline compound tantalum sulfide (Ta₃S₂) with new and novel properties beyond TaAs. Crucially, our results show that Ta₃S₂ has the largest k-space separation between Weyl nodes among known Weyl semimetal candidates, which is about twice larger than the measured value in TaAs and 20 times larger than the predicted value in WTe₂. Moreover, all Weyl nodes in Ta₃S₂ are of type II. Therefore, Ta₃S₂ is a type II Weyl semimetal. Furthermore, we predict that increasing the lattice by <4% can annihilate all Weyl nodes, driving a novel topological metal-to-insulator transition from amore » Weyl semimetal state to a topological insulator state. The robust type II Weyl semimetal state and the topological metal-to-insulator transition in Ta₃S₂ are potentially useful in device applications. Our methodology can be generally applied to search for new Weyl semimetals.« less

Authors:

Chang, Guoqing ^[1]; Xu, Su-Yang ^[2]; Sanchez, Daniel S. ^[2]; Huang, Shin-Ming ^[1]; Lee, Chi-Cheng ^[1]; Chang, Tay-Rong ^[3]; Bian, Guang ^[2]; Zheng, Hao ^[2]; Belopolski, Ilya ^[2]; Alidoust, Nasser ^[2]; Jeng, Horng-Tay ^[4]; Bansil, Arun ^[5]; Lin, Hsin ^[1]; Hasan, M. Zahid ^[2]

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+ Show Author Affiliations

1. National Univ. of Singapore (Singapore). Center for Advanced 2D Materials and Graphene Research Center and Dept. of Physics
2. Princeton Univ., NJ (United States). Lab. for Topological Quantum Matter and Spectroscopy and Dept. of Physics
3. Princeton Univ., NJ (United States). Lab. for Topological Quantum Matter and Spectroscopy and Dept. of Physics; National Tsing Hua Univ., Hsinchu (Taiwan). Dept. of Physics
4. National Tsing Hua Univ., Hsinchu (Taiwan). Dept. of Physics; Academia Sinica, Taipei (Taiwan). Inst. of Physics
5. Northeastern Univ., Boston, MA (United States). Dept. of Physics

Publication Date:

Fri Jun 24 00:00:00 EDT 2016

Research Org.:

Northeastern Univ., Boston, MA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES); USDOE Office of Science (SC), Advanced Scientific Computing Research (ASCR); National Research Foundation of Korea (NRF); National Science Council (NSC); National Energy Research Scientific Computing Center (NERSC); Gordon and Betty Moore Foundation

OSTI Identifier:

1466571

Grant/Contract Number:  

FG02-07ER46352; FG-02-05ER46200; NRF-NRFF2013-03; AC02-05CH11231; GBMF4547

Resource Type:

Accepted Manuscript

Journal Name:

Science Advances

Additional Journal Information:

Journal Volume: 2; Journal Issue: 6; Journal ID: ISSN 2375-2548

Publisher:

AAAS

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; Weyl fermion; Fermi arc; Topology