Observation of a chiral wave function in the twofold-degenerate quadruple Weyl system BaPtGe

Haoxiang Li, Tiantian Zhang, A. Said, Y. Fu, G. Fabbris, D. G. Mazzone, J. Zhang, J. Lapano, H. N. Lee, H. C. Lei, M. P. M. Dean, S. Murakami, and H. Miao
Phys. Rev. B 103, 184301 – Published 4 May 2021
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Abstract

Topological states in quantum materials are defined by bulk wave functions that possess nontrivial topological invariants. While edge modes are widely presented as signatures of nontrivial topology, how bulk wave functions can manifest explicitly topological properties remains unresolved. Here, using high-resolution inelastic x-ray spectroscopy (IXS) combined with first principles calculations, we report experimental signatures of chiral wave functions in the bulk phonon spectrum of BaPtGe, which we show to host a previously undiscovered twofold-degenerate quadruple Weyl node. The chirality of the degenerate phononic wave function yields a nontrivial phonon dynamical structure factor, S(Q,ω), along high-symmetry directions, that is in excellent agreement with numerical and model calculations. Our results establish IXS as a powerful tool to uncover topological wave functions, providing a key missing ingredient in the study of topological quantum matter.

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  • Received 29 October 2020
  • Accepted 16 April 2021

DOI:https://doi.org/10.1103/PhysRevB.103.184301

©2021 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Haoxiang Li1,*, Tiantian Zhang2,3,*,†, A. Said4,*, Y. Fu5, G. Fabbris4, D. G. Mazzone6, J. Zhang1, J. Lapano1, H. N. Lee1, H. C. Lei5,‡, M. P. M. Dean7, S. Murakami2,3, and H. Miao1,§

  • 1Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
  • 2Department of Physics, Tokyo Institute of Technology, Okayama, Meguro-ku, Tokyo 152-8551, Japan
  • 3Tokodai Institute for Element Strategy, Tokyo Institute of Technology, Nagatsuta, Midori-ku, Yokohama, Kanagawa 226-8503, Japan
  • 4Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
  • 5Department of Physics and Beijing Key Laboratory of Opto-Electronic Functional Materials and Micro-devices, Renmin University of China, Beijing, China
  • 6Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
  • 7Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA

  • *These authors contributed equally to this work.
  • ttzhang@stat.phys.titech.ac.jp
  • hlei@ruc.edu.cn
  • §miaoh@ornl.gov

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Issue

Vol. 103, Iss. 18 — 1 May 2021

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