Title: New type of Weyl semimetal with quadratic double Weyl fermions

Abstract

Weyl semimetals have attracted worldwide attention due to their wide range of exotic properties predicted in theories. The experimental realization had remained elusive for a long time despite much effort. Very recently, the first Weyl semimetal has been discovered in an inversion-breaking, stoichiometric solid TaAs. So far, the TaAs class remains the only Weyl semimetal available in real materials. To facilitate the transition of Weyl semimetals from the realm of purely theoretical interest to the realm of experimental studies and device applications, it is of crucial importance to identify other robust candidates that are experimentally feasible to be realized. In this paper, we propose such a Weyl semimetal candidate in an inversion-breaking, stoichiometric compound strontium silicide, SrSi₂, with many new and novel properties that are distinct from TaAs. Here, we show that SrSi₂ is a Weyl semimetal even without spin-orbit coupling and that, after the inclusion of spin-orbit coupling, two Weyl fermions stick together forming an exotic double Weyl fermion with quadratic dispersions and a higher chiral charge of ±2. Moreover, we find that the Weyl nodes with opposite charges are located at different energies due to the absence of mirror symmetry in SrSi₂, paving the way for the realizationmore » of the chiral magnetic effect. Finally, our systematic results not only identify a much-needed robust Weyl semimetal candidate but also open the door to new topological Weyl physics that is not possible in TaAs« less

Authors:

Huang, Shin-Ming ^[1]; Xu, Su-Yang ^[2]; Belopolski, Ilya ^[2]; Lee, Chi-Cheng ^[1]; Chang, Guoqing ^[1]; Chang, Tay-Rong ^[3]; Wang, BaoKai ^[4]; Alidoust, Nasser ^[2]; Bian, Guang ^[2]; Neupane, Madhab ^[2]; Sanchez, Daniel ^[2]; Zheng, Hao ^[2]; Jeng, Horng-Tay ^[5]; Bansil, Arun ^[6]; Neupert, Titus ^[7]; Lin, Hsin ^[1]; Hasan, M. Zahid ^[2]

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+ Show Author Affiliations

1. Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore 117546,, Department of Physics, National University of Singapore, Singapore 117542,
2. Joseph Henry Laboratory, Department of Physics, Princeton University, Princeton, NJ 08544,
3. Joseph Henry Laboratory, Department of Physics, Princeton University, Princeton, NJ 08544,, Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan,, Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ 08544,
4. Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore 117546,, Department of Physics, National University of Singapore, Singapore 117542,, Department of Physics, Northeastern University, Boston, MA 02115,
5. Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan,, Institute of Physics, Academia Sinica, Taipei 11529, Taiwan,
6. Department of Physics, Northeastern University, Boston, MA 02115,
7. Princeton Center for Theoretical Science, Princeton University, Princeton, NJ 08544

Publication Date:

Tue Jan 19 00:00:00 EST 2016

Research Org.:

Princeton Univ., NJ (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1236659

Alternate Identifier(s):

OSTI ID: 1347702

Grant/Contract Number:  

FG-02-05ER46200; FG02-05ER46200; FG02-07ER46352; AC02-05CH11231

Resource Type:

Published Article

Journal Name:

Proceedings of the National Academy of Sciences of the United States of America

Additional Journal Information:

Journal Name: Proceedings of the National Academy of Sciences of the United States of America Journal Volume: 113 Journal Issue: 5; Journal ID: ISSN 0027-8424

Publisher:

Proceedings of the National Academy of Sciences

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; Fermi arc; Weyl fermion; chiral magnetic effect; topological insulator