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Title: Unconventional Chiral Fermions and Large Topological Fermi Arcs in RhSi

Abstract

The theoretical proposal of chiral fermions in topological semimetals has led to a significant effort towards their experimental realization. In particular, the Fermi surfaces of chiral semimetals carry quantized Chern numbers, making them an attractive platform for the observation of exotic transport and optical phenomena. While the simplest example of a chiral fermion in condensed matter is a conventional |C|=1 Weyl fermion, recent theoretical works have proposed a number of unconventional chiral fermions beyond the standard model which are protected by unique combinations of topology and crystalline symmetries. However, materials candidates for experimentally probing the transport and response signatures of these unconventional fermions have thus far remained elusive. In this Letter, we propose the RhSi family in space group No. 198 as the ideal platform for the experimental examination of unconventional chiral fermions. We find that RhSi is a filling-enforced semimetal that features near its Fermi surface a chiral double sixfold-degenerate spin-1 Weyl node at R and a previously uncharacterized fourfold-degenerate chiral fermion at Γ. Each unconventional fermion displays Chern number ±4 at the Fermi level. We also show that RhSi displays the largest possible momentum separation of compensative chiral fermions, the largest proposed topologically nontrivial energy window, and themore » longest possible Fermi arcs on its surface. We conclude by proposing signatures of an exotic bulk photogalvanic response in RhSi.« less

Authors:
; ; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). National Energy Research Scientific Computing Center (NERSC)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1544354
DOE Contract Number:  
FG02-07ER46352; AC02-05CH11231
Resource Type:
Journal Article
Journal Name:
Physical Review Letters
Additional Journal Information:
Journal Volume: 119; Journal Issue: 20; Journal ID: ISSN 0031-9007
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English

Citation Formats

Chang, Guoqing, Xu, Su-Yang, Wieder, Benjamin J., Sanchez, Daniel S., Huang, Shin-Ming, Belopolski, Ilya, Chang, Tay-Rong, Zhang, Songtian, Bansil, Arun, Lin, Hsin, and Hasan, M. Zahid. Unconventional Chiral Fermions and Large Topological Fermi Arcs in RhSi. United States: N. p., 2017. Web. doi:10.1103/PhysRevLett.119.206401.
Chang, Guoqing, Xu, Su-Yang, Wieder, Benjamin J., Sanchez, Daniel S., Huang, Shin-Ming, Belopolski, Ilya, Chang, Tay-Rong, Zhang, Songtian, Bansil, Arun, Lin, Hsin, & Hasan, M. Zahid. Unconventional Chiral Fermions and Large Topological Fermi Arcs in RhSi. United States. doi:10.1103/PhysRevLett.119.206401.
Chang, Guoqing, Xu, Su-Yang, Wieder, Benjamin J., Sanchez, Daniel S., Huang, Shin-Ming, Belopolski, Ilya, Chang, Tay-Rong, Zhang, Songtian, Bansil, Arun, Lin, Hsin, and Hasan, M. Zahid. Wed . "Unconventional Chiral Fermions and Large Topological Fermi Arcs in RhSi". United States. doi:10.1103/PhysRevLett.119.206401.
@article{osti_1544354,
title = {Unconventional Chiral Fermions and Large Topological Fermi Arcs in RhSi},
author = {Chang, Guoqing and Xu, Su-Yang and Wieder, Benjamin J. and Sanchez, Daniel S. and Huang, Shin-Ming and Belopolski, Ilya and Chang, Tay-Rong and Zhang, Songtian and Bansil, Arun and Lin, Hsin and Hasan, M. Zahid},
abstractNote = {The theoretical proposal of chiral fermions in topological semimetals has led to a significant effort towards their experimental realization. In particular, the Fermi surfaces of chiral semimetals carry quantized Chern numbers, making them an attractive platform for the observation of exotic transport and optical phenomena. While the simplest example of a chiral fermion in condensed matter is a conventional |C|=1 Weyl fermion, recent theoretical works have proposed a number of unconventional chiral fermions beyond the standard model which are protected by unique combinations of topology and crystalline symmetries. However, materials candidates for experimentally probing the transport and response signatures of these unconventional fermions have thus far remained elusive. In this Letter, we propose the RhSi family in space group No. 198 as the ideal platform for the experimental examination of unconventional chiral fermions. We find that RhSi is a filling-enforced semimetal that features near its Fermi surface a chiral double sixfold-degenerate spin-1 Weyl node at R and a previously uncharacterized fourfold-degenerate chiral fermion at Γ. Each unconventional fermion displays Chern number ±4 at the Fermi level. We also show that RhSi displays the largest possible momentum separation of compensative chiral fermions, the largest proposed topologically nontrivial energy window, and the longest possible Fermi arcs on its surface. We conclude by proposing signatures of an exotic bulk photogalvanic response in RhSi.},
doi = {10.1103/PhysRevLett.119.206401},
journal = {Physical Review Letters},
issn = {0031-9007},
number = 20,
volume = 119,
place = {United States},
year = {2017},
month = {11}
}

Works referenced in this record:

Z2 Topological Order and the Quantum Spin Hall Effect
journal, September 2005


Colloquium: Topological insulators
journal, November 2010


Quantum Spin Hall Effect and Topological Phase Transition in HgTe Quantum Wells
journal, December 2006

  • Bernevig, B. A.; Hughes, T. L.; Zhang, S.-C.
  • Science, Vol. 314, Issue 5806, p. 1757-1761
  • DOI: 10.1126/science.1133734