Optical signatures of multifold fermions in the chiral topological semimetals RhSi and CoSi

ORAL

Abstract

The chiral topological semimetals RhSi and CoSi exhibit band degeneracies near the Fermi level enforced by the crystal symmetries. The low-energy quasiparticles emerging near these band degeneracies, referred to as multifold fermions, have no counterpart as elementary fermionic particles. We calculate the linear optical conductivity of all chiral multifold fermions[1] and show that it provides an experimental fingerprint for each type of multifold fermion. We use a tight-binding model for space group 198, where RhSi and CoSi crystallize, and obtain the parameters for both materials from first-principles calculations. The results reveal that the location of the chemical potential is crucial to understand the optical response seen in experiments[2,3], determined at low energies by the threefold fermion at the Γ point in both materials, and providing signatures of the existence of a spin-3/2 fourfold fermion in CoSi.

[1] M.-Á S.-M. et al., Phys. Rev. B, 99 155145 (2019).
[2] B. Xu et al, PNAS Nov 2020, 117 (44) 27104-27110
[3] Z. Ni et al., arXiv:2005.13473 (2020).

*This work is supported by the ANR, grant ANR-18-CE30-0001-01 (TOPODRIVE), and the European Union grant agreements No. 829044 (SCHINES) and No. 754303 (MSCA GreQue Cofund).

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Presenters

  • Miguel Ángel Sánchez Martínez

    • Institut Neel, CNRS and Universite Grenoble Alpes

Authors

  • Miguel Ángel Sánchez Martínez

    • Institut Neel, CNRS and Universite Grenoble Alpes

  • Bing XU

    • University of Fribourg
    • Department of Physics and Fribourg Center for Nanomaterials,, University of Fribourg

  • Zhenyao Fang

    • Department of Chemistry, University of Pennsylvania

  • Zhuoliang Ni

    • University of Pennsylvania
    • Department of Physics and Astronomy, University of Pennsylvania

  • Jorn W. F. Venderbos

    • Department of Physics, Drexel University, Philadelphia, PA 19104, USA
    • Drexel University
    • Department of Physics, Department of Materials Science and Engineering, Drexel University

  • Fernando De Juan

    • Donostia International Physics Center
    • Donostia International Physics Center and IKERBASQUE, Basque Foundation for Science

  • Eugene John Mele

    • Department of Physics and Astronomy, University of Pennsylvania
    • University of Pennsylvania

  • Andrew Marshall Rappe

    • Chemistry, University of Pennsylvania
    • University of Pennsylvania
    • Department of Chemistry, University of Pennsylvania

  • Adolfo G Grushin

    • Institut Néel, CNRS and Université Grenoble Alpes
    • Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel
    • Institut Neel
    • CNRS Institut Néel
    • Institut Neel, CNRS and Universite Grenoble Alpes

  • Liang Wu

    • University of Pennsylvania
    • Department of Physics and Astronomy, University of Pennsylvania