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Optical signatures of multifold fermions in the chiral topological semimetal CoSi

Journal Article · · Proceedings of the National Academy of Sciences of the United States of America
 [1];  [2];  [3];  [4];  [5];  [2];  [6];  [7];  [8];  [1];  [9];  [5];  [3];  [2];  [5]
  1. Fribourg Center for Nanomaterials, Department of Physics, University of Fribourg, CH-1700 Fribourg, Switzerland,
  2. Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6323,
  3. Institut Néel, CNRS and Université Grenoble Alpes, 38042 Grenoble, France,
  4. Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104,, Department of Physics, Drexel University, Philadelphia, PA 19104,, Department of Materials Science and Engineering, Drexel University, Philadelphia, PA 19104,
  5. Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104,
  6. Max Planck Institut fur Chemische Physik fester Stoffe, 01187 Dresden, Germany,
  7. Maryland Quantum Materials Center, Department of Physics, University of Maryland, College Park, MD 20742,
  8. Maryland Quantum Materials Center, Department of Physics, University of Maryland, College Park, MD 20742,, Canadian Institute for Advanced Research, Toronto, Ontario M5G 1Z8, Canada
  9. Max Planck Institut fur Chemische Physik fester Stoffe, 01187 Dresden, Germany,, Canadian Institute for Advanced Research, Toronto, Ontario M5G 1Z8, Canada
Significance

We present a comprehensive combined experimental and theoretical study of optical conductivity in the chiral topological semimetal CoSi based on the development of high-quality crystals. We reveal the presence and the energy range of various exotic multifold quasiparticles in the optical responses and provide experimental evidence for the realization of fourfold spin-3/2 fermions, which were not directly observed previously. Our work is critical to interpreting future optical and transport responses of multifold fermion materials. We believe the methods used in this work will not only stimulate future research in this class of materials but will also provide a strategy for addressing optical signatures of chiral topological fermions in solids.

Research Organization:
Univ. of Pennsylvania, Philadelphia, PA (United States)
Sponsoring Organization:
USDOE; USDOE Office of Science (SC)
Grant/Contract Number:
FG02-07ER46431
OSTI ID:
1678771
Alternate ID(s):
OSTI ID: 1849795
OSTI ID: 1867826
Journal Information:
Proceedings of the National Academy of Sciences of the United States of America, Journal Name: Proceedings of the National Academy of Sciences of the United States of America Journal Issue: 44 Vol. 117; ISSN 0027-8424
Publisher:
Proceedings of the National Academy of SciencesCopyright Statement
Country of Publication:
United States
Language:
English

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