RT Journal Article
SR Electronic
T1 A strongly robust type II Weyl fermion semimetal state in Ta<sub>3</sub>S<sub>2</sub>
JF Science Advances
JO Sci Adv
FD American Association for the Advancement of Science
DO 10.1126/sciadv.1600295
VO 2
IS 6
A1 Chang, Guoqing
A1 Xu, Su-Yang
A1 Sanchez, Daniel S.
A1 Huang, Shin-Ming
A1 Lee, Chi-Cheng
A1 Chang, Tay-Rong
A1 Bian, Guang
A1 Zheng, Hao
A1 Belopolski, Ilya
A1 Alidoust, Nasser
A1 Jeng, Horng-Tay
A1 Bansil, Arun
A1 Lin, Hsin
A1 Hasan, M. Zahid
YR 2016
UL http://advances.sciencemag.org/content/2/6/e1600295.abstract
AB 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. 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 &lt;4% can annihilate all Weyl nodes, driving a novel topological metal-to-insulator transition from a 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.