Collective plasmonic modes in the chiral multifold fermionic material CoSi

ORAL

Abstract

Plasmonics in topological semimetals offers exciting opportunities for fundamental physics exploration as well as for technological applications. Here, we investigate plasmons in the exemplar chiral crystal CoSi, which hosts a variety of multifold fermionic excitations. We show that CoSi hosts two distinct plasmon modes in the infrared regime at 0.1 eV and 1.1 eV in the long-wavelength limit. The 0.1 eV plasmon is found to be highly dispersive, and originates from intraband collective oscillations associated with double spin-1 excitation, while the 1.1 eV plasmon is dispersionless and it involves interband correlations. Both plasmon modes lie outside the particle-hole continuum and possess a long lifetime. Our study indicates that the CoSi class of materials will provide an interesting materials platform for exploring fundamental and technological aspects of topological plasmonics.

*D.D. and A.A. acknowledge the Science and Engineering Research Board (SERB) and the Department of Science and Technology, India. The work at Northeastern University was supported by the Air Force Office of Scientific Research under award number FA9550-20-1-0322, and it benefited from the computational resources of Northeastern University's Advanced Scientific Computation Center (ASCC) and the Discovery Cluster.

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Presenters

  • Barun Ghosh

    • Northeastern University, Boston, USA
    • Department of Physics, Northeastern University, USA

Authors

  • Barun Ghosh

    • Northeastern University, Boston, USA
    • Department of Physics, Northeastern University, USA

  • Debasis Dutta

    • Department of Physics, Indian Institute of Technology, Kanpur, India

  • Bahadur Singh

    • Tata Institute of Fundamental Research
    • Tata Institute for Fundamental Research
    • TIFR
    • Tata Institute of Fundamental Research, Mumbai
    • Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Mumbai, India

  • Hsin Lin

    • Academia Sinica
    • Institute of Physics, Academia Sinica, Taiwan

  • Antonio Politano

    • INSTM and Department of Physical and Chemical Sciences, University of L'Aquila, Italy; CNR-IMM Istituto per la Microelettronica e Microsistemi, Italy

  • Arun Bansil

    • Northeastern University
    • Department of Physics, Northeastern University, USA

  • Amit Agarwal

    • IIT Kanpur, India
    • Department of Physics, Indian Institute of Technology, Kanpur, India