Direct Wavefunction Detection of Lattice Vibrations by Inelastic Neutron Scattering

ORAL

Abstract

In close analogy to electronic semimetals, a variety of Weyl, Dirac points and nodal lines are predicted for phonons recently by ab initio calculations. However, very few experimental confirmations have been made, and most of them focused on bulk dispersions only. In this talk, we will present the results of our Inelastic Neutron Scattering (INS) experiments on MnSi and CoSi crystals. The measured phononic band structures and coherent cross sections are in remarkable agreement with our DFPT calculations, which enabled us to explore multiple types of unconventional Weyl and Dirac points in the Brillioun zone. Furthermore, being aware of neutron scattering's capability of wavefunction detection and polarization determination, we derived an explicit relation between the topological invariant of a Weyl node and the INS intensities nearby. Apart from protected surface states and novel transport phenomena, our work suggests that topological nodes also leave some observable traces in spectroscopic patterns.

*This work is supported by the NSF of China under Grant No.11874069 and No.11888101, and by the NBRP of China under Grant No.2018YFA0305602 and No.2015CB921302.

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Presenters

  • Yiran Liu

    • International Center for Quantum Materials, School of Physics, Peking University

Authors

  • Zhendong Jin

    • International Center for Quantum Materials, School of Physics, Peking University

  • Biaoyan Hu

    • International Center for Quantum Materials, School of Physics, Peking University

  • Yiran Liu

    • International Center for Quantum Materials, School of Physics, Peking University

  • Yangmu Li

    • Brookhaven National Laboratory
    • Condensed Matter Physics and Materials Science Division, Brookhaven National Laboratory

  • Tiantian Zhang

    • Department of Physics, Tokyo Institute of Technology
    • Beijing National Laboratory for Condensed Matter Physics, and Institute of Physics, Chinese Academy of Sciences
    • Tokyo Inst of Tech - Tokyo

  • Kazuki Iida

    • Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society (CROSS)

  • Kazuya Kamazawa

    • Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society (CROSS)

  • Alexander Kolesnikov

    • Spallation Neutron Source, Oak Ridge National Laboratory
    • Neutron Scattering Division, Oak Ridge National Lab
    • Oak Ridge National Lab
    • Neutron Scattering Division, Oak Ridge National Laboratory
    • ORNL
    • Oak Ridge National Laboratory

  • Matthew Brandon Stone

    • Oak Ridge National Lab
    • Oak Ridge national lab
    • Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
    • Neutron Scattering Division, Oak Ridge National Laboratory
    • Oak Ridge National Laboratory
    • Oakridge National Laboratory

  • Xiangyu Zhang

    • State Key Laboratory for Advance Metals and Materials, University of Science and Technology Beijing

  • Haiyang Chen

    • State Key Laboratory for Advance Metals and Materials, University of Science and Technology Beijing

  • Yandong Wang

    • State Key Laboratory for Advance Metals and Materials, University of Science and Technology Beijing

  • Igor Zaliznyak

    • Brookhaven National Laboratory
    • Condensed Matter Physics and Materials Science Division, Brookhaven National Laboratory

  • John Tranquada

    • Brookhaven National Laboratory
    • Brookhaven national lab
    • Condensed Matter Physics and Materials Science Division, Brookhaven National Laboratory

  • Chen Fang

    • Chinese Academy of Sciences,Institute of Physics
    • Institute of Physics, Chinese Academy of Sciences
    • Beijing National Laboratory for Condensed Matter Physics, and Institute of Physics, Chinese Academy of Sciences
    • Institute of Physics, chinese academy of sciences

  • Yuan Li

    • International Center for Quantum Materials, School of Physics, Peking University
    • Peking University
    • Peking Univ
    • International Cent re for Quantum Materials, School of Physics, Peking University, Beijing, Peking Univ