Tuning the electron-phonon coupling in MX<sub>2</sub> system

ORAL  · Invited

Abstract

Whereas electron-phonon scattering relaxes the electron’s momentum in metals, a perpetual exchange of momentum between phonons and electrons may conserve total momentum and lead to a coupled electron-phonon liquid. In a previous study, we presented evidence of such an electron-phonon liquid in NbGe2 [1], which could be a platform for observing electron hydrodynamics. Here we provide evidence on tuning the strength of electron-phonon coupling by replacing Ge with Si and Nb with Ta. We combine de Haas-van Alphen (dHvA), electron transport, Raman scattering, and first-principles calculations in this MX2 topological semimetal family where M=Nb, Ta and X=Ge, Si [2]. Tuning electron-phonon coupling increases the transport mobilities from nearly balanced to an order magnitude larger than quantum mobilities, with crystal structure or topology unchanged, and small differences in electron Fermi surface. Simultaneously, Raman scattering and first-principles calculations demonstrate a dominant phonon-drag effect only in MGe2 compounds. Our study suggests phonon-drag as a mechanism for achieving electron-phonon hydrodynamics.

*The work at Boston College was funded by the U.S. Department of Energy (DOE), Office of Basic Energy Sciences, Division of Physical Behavior of Materials, under Awards No. DE-SC0023124 and No. DE-SC0018675.

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Publication: [1] Yang, H.-Y., Yao, X., Plisson, V., Burch, K. S. & Tafti, F. Evidence of a coupled electron-phonon liquid in NbGe2. Nat. Comm. 12, 5292 (2021).
[2] Yao, X.*, Plisson, V.*, Wang, Y., et al, Direct Evidence Phonons Produce Anomalously Large Electronic Transport in Topological Semimetals (2023, in review)

Presenters

  • Xiaohan Yao

    • Boston College

Authors

  • Xiaohan Yao

    • Boston College

  • Vincent M Plisson

    • Boston College

  • Yaxian Wang

    • Institute of Physics, Chinese Academy of Sciences)

  • George Varnavides

    • University of California, Los Angeles

  • Alexey Suslov

    • National High Magnetic Field Laboratory
    • National High Magnetic Field Laboratory, Florida State University

  • David E Graf

    • Florida State University
    • National High Magnetic Fields Laboratory, Florida State University
    • National High Magnetic Field Laboratory, Florida State University

  • Eun Sang Choi

    • National High Magnetic Field Laboratory
    • National High Magnetic Field Lab, Tallahassee, Florida
    • NHMFL
    • MagLab
    • Florida State University
    • National High Magnetic Field Laboratory, Florida State University

  • Hung-Yu Yang

    • Boston College

  • Yiping Wang

    • Boston College

  • Marisa L Romanelli

    • University of Illinois at Urbana-Champai
    • University of Illinois at Urbana-Champaign
    • Boston College

  • Grant McNamara

    • Boston College

  • Birender Singh

    • Boston college

  • Gregory T McCandless

    • Baylor University

  • Julia Y Chan

    • Baylor University

  • Prineha Narang

    • College of Letters and Science, University of California, Los Angeles (UCLA), CA, USA.
    • University of California Los Angeles
    • College of Letters and Science, University of California, Los Angeles (UCLA)
    • UCLA
    • University of California, Los Angeles
    • College of Letters and Science, University of California, Los Angeles
    • Harvard University

  • Fazel Tafti

    • Boston College

  • Kenneth S Burch

    • Boston College