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)

*This work was supported by the Department of Energy, Office of Basic Energy Sciences, Early Career Award Program under Award No. 1047478. Work at Brookhaven National Laboratory was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract No. DE- SC0012704.

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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