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

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, SrSi 2, with many new and novel properties that are distinct from TaAs. Here, we show that SrSi 2 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 SrSi 2, paving the waymore » for the realization 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
 [1] ;  [2] ;  [2] ;  [1] ;  [1] ;  [3] ;  [4] ;  [2] ;  [2] ;  [2] ;  [2] ;  [2] ;  [5] ;  [6] ;  [2] ;  [1] ;  [2]
  1. National Univ. of Singapore (Singapore)
  2. Princeton Univ., Princeton, NJ (United States)
  3. Princeton Univ., Princeton, NJ (United States); National Tsing Hua Univ., Hsinchu (Taiwan)
  4. National Univ. of Singapore (Singapore); Northeastern Univ., Boston, MA (United States)
  5. National Tsing Hua Univ., Hsinchu (Taiwan); Academia Sinica, Taipei (Taiwan)
  6. Northeastern Univ., Boston, MA (United States)
Publication Date:
Grant/Contract Number:
FG02-05ER46200; FG02-07ER46352; AC02-05CH11231; FG-02-05ER46200
Published Article
Journal Name:
Proceedings of the National Academy of Sciences of the United States of America
Additional Journal Information:
Journal Volume: 113; Journal Issue: 5; Journal ID: ISSN 0027-8424
National Academy of Sciences, Washington, DC (United States)
Research Org:
Princeton Univ., NJ (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
36 MATERIALS SCIENCE; 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; Fermi arc; Weyl fermion; chiral magnetic effect; topological insulator
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1347702