Chiral pumping at THz frequencies in Weyl semimetal TaAs

ORAL

Abstract

An optical conductivity enhancement is observed at THz frequencies with polarization parallel to an
applied magnetic field. The effect is studied in single crystal TaAs samples utilizing FTIR spectroscopy in
static magnetic fields in the Voigt geometry. The enhanced conductivity, most clearly observed with
fields oriented parallel to either the a- or c- crystal axis, is understood in the context of Weyl state chiral
pumping. Results from applied magnetic fields up to 8T that span the semi-classical and quantum limits
in both kinds of Weyl states are compared to theoretical predictions. Magnetic field dependent
scattering rates in both regimes and geometrical Fermi surface considerations will also be discussed. The
Landau level spectrum of the Weyl states are measured in the E⊥B Voigt geometry and analyzed within
a model of Weyl state pairs, allowing extraction of conduction-valence band asymmetries and the
Lifshitz gap energy.

*Work at the University of Maryland is supported by National Science Foundation (NSF) under award number 1610554. Work at UCLA was supported by the Department of Energy (DOE) under award number DE-SC0011978.

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Presenters

  • Antonio Levy

    • Center for Nanophysics and Advanced Materials and Department of Physics, University of Maryland

Authors

  • Antonio Levy

    • Center for Nanophysics and Advanced Materials and Department of Physics, University of Maryland

  • Andrei Sushkov

    • University of Maryland
    • Center for Nanophysics and Advanced Materials and Department of Physics, University of Maryland

  • Fengguang Liu

    • Center for Nanophysics and Advanced Materials and Department of Physics, University of Maryland

  • Howard Drew

    • Center for Nanophysics and Advanced Materials and Department of Physics, University of Maryland

  • Bing Shen

    • Physics, University of California at Los Angeles
    • Department of Physics and Astronomy and California NanoSystems Institute, University of California, Los Angeles
    • Physics, University of California, Los Angeles
    • Physics and Astronomy, Univ of California - Los Angeles

  • Ni Ni

    • Physics, University of California at Los Angeles
    • Physics and Astronomy, Univ of California - Los Angeles
    • Department of Physics and Astronomy and California NanoSystems Institute, University of California, Los Angeles
    • Department of Physics and Astronomy , Univ of California - Los Angeles

  • Gregory Jenkins

    • Center for Nanophysics and Advanced Materials and Department of Physics, University of Maryland