Observation of Double Weyl Phonons in Parity-Breaking FeSi

ORAL

Abstract

Condensed matter systems have now become a fertile ground to discover emerging topological quasiparticles with symmetry protected modes. While many studies have focused on fermionic excitations, the same conceptual framework can also be applied to bosons yielding new types of topological states. Motivated by Zhang et al.’s recent theoretical prediction of double Weyl phonons in transition metal monosilicides [Phys. Rev. Lett. 120, 016401 (2018)], we directly measure the phonon dispersion in parity-breaking FeSi using inelastic x-ray scattering. By comparing the experimental data with theoretical calculations, we make the first observation of double Weyl points in FeSi, which will be an ideal material to explore emerging bosonic excitations and its topologically nontrivial properties.
Physical Review Letters 121, 035302 (2018)

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Presenters

  • Mark Dean

    Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Department of Condensed Matter Physics and Materials Science, Upton, New York 11973, USA, Brookhaven National Laboratory, BNL, Brookhaven National Laboratory, Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory

Authors

  • Hu Miao

    BNL, Brookhaven National Laboratory, Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory

  • Tiantian Zhang

    Institute of physics, Chinese Academy of Sciences, Institute of Physics CAS, Institute of Physics

  • Le Wang

    Institute of Physics, Chinese Academy of Sciences, Institute of Physics

  • Derek Meyers

    Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Materials Science and Engineering, University of California, Berkeley, Brookhaven National Laboratory

  • Ayman Said

    Argonne National Laboratory, Argonne Natl Lab, Advanced Photon Source, Argonne National Laboratory

  • Yilin Wang

    Department of Condensed Matter Physics and Materials Science, Upton, New York 11973, USA, Brookhaven National Laboratory, Brookhaven National Laboratory, Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, NY

  • Youguo Shi

    Institute of Physics, Chinese Academy of Sciences, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Chinese Academy of Sciences, Institute of Physics

  • Hongming Weng

    Institute of Physics, Chinese Academy of Sciences, Institute of physics, Chinese Academy of Sciences, Chinese Academy of Sciences, Institute of Physics CAS, Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Institute of Physics

  • Zhong Fang

    Institute of Physics CAS, Institute of Physics

  • Mark Dean

    Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Department of Condensed Matter Physics and Materials Science, Upton, New York 11973, USA, Brookhaven National Laboratory, BNL, Brookhaven National Laboratory, Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory