Shot noise indicates the lack of quasiparticles in a strange metal

ORAL  · Invited

Abstract

Understanding of strange metal properties, observed in materials from the high-temperature superconductors to heavy fermion metals and van der Waals structures, is an outstanding challenge. In conventional metals, current is carried by quasiparticles with charge of magnitude e, and while it has been suggested that quasiparticles are absent in strange metals, direct experimental evidence is lacking. We examine short, diffusive nanowires of the heavy fermion strange metal YbRh2Si2 and discover strongly suppressed shot noise compared to conventional metals. In contrast, shot noise measurements in short, diffusive gold nanowires are consistent with theoretical expectations for Fermi liquids. Using Johnson-Nyquist noise measurements in long wires, we find an electron-phonon coupling in this material comparable to that of gold, confirming that the suppression of noise seen in the strange metal samples is not due to electron-phonon effects. Shot noise probes the effective charge, or the granularity of the current-carrying excitations. With no other known mechanism to suppress the shot noise, the experimentally observed suppression implies that the current is not carried by well-defined quasiparticles in YbRh2Si2. Our work sets the stage for similar studies on other strange metals to test the universality of this result, and for future experiments at lower temperatures to examine the shot noise as the material is field-tuned between the Fermi liquid and strange metal regimes.

*This work was supported by US Department of Energy, Basic Energy Sciences, Experimental Condensed Matter Physics award DE-FG02-06ER46337, US National Science Foundation DMR-1704264, European Research Council ERC Advanced Grant 227378, Austrian Science Fund FWF W1243, P29279-N27, P29296-N27 (SP), European Union Horizon 2020 grant agreement 824109-EMP, Austrian Research Promotion Agency FFG 883941, US Air Force Office of Scientific Research FA9550-17-1-0340 (AMA) US National Science Foundation DMR-1920740, and Robert A. Welch Foundation Grant C-1411.

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Publication: https://arxiv.org/abs/2206.00673

Presenters

  • Douglas Natelson

    • Rice University
    • Department of Physics and Astronomy, Department of Electrical and Computer Engineering, Department of Materials Science and NanoEngineering, Rice University

Authors

  • Douglas Natelson

    • Rice University
    • Department of Physics and Astronomy, Department of Electrical and Computer Engineering, Department of Materials Science and NanoEngineering, Rice University

  • Liyang Chen

    • Rice University

  • Dale T Lowder

    • Rice University

  • Emine Bakali

    • Institute of Solid State Physics, TU Wien
    • Institute of Solid State Physics, Technischen Universita¨t (TU) Wien, Wiedner Hauptstraße 8-10, 1040 Vienna, Austria

  • Aaron M Andrews

    • Institute of Solid State Electronics, TU Wien
    • Institute of Solid State Electronics, TU Wien, Nanocenter Campus Gußhaus, Gußhausstraße 25-25a, Geba¨ude CH, 1040 Vienna, Austria

  • Werner Schrenk

    • Institute of Solid State Electronics, Center for Micro and Nanostructures, TU Wien
    • Institute of Solid State Electronics, TU Wien, Nanocenter Campus Gußhaus, Gußhausstraße 25-25a, Geba¨ude CH, 1040 Vienna, Austria

  • Monika Waas

    • Institute of Solid State Physics, TU Wien
    • Institute of Solid State Physics, Technischen Universita¨t (TU) Wien, Wiedner Hauptstraße 8-10, 1040 Vienna, Austria.

  • Robert Svagera

    • Institute of Solid State Physics, TU Wien
    • Institute of Solid State Physics, Technischen Universita¨t (TU) Wien, Wiedner Hauptstraße 8-10, 1040 Vienna, Austria.

  • Gaku Eguchi

    • Institute of Solid State Physics, Vienna University of Technology, Vienna, Austria
    • Institute of Solid State Physics, TU Wien
    • Vienna University of Technology
    • Institute of Solid State Physics, Technischen Universita¨t (TU) Wien, Wiedner Hauptstraße 8-10, 1040 Vienna, Austria.

  • Lukas Prochaska

    • Vienna Univ of Technology

  • Qimiao Si

    • Rice University

  • Silke Buehler-Paschen

    • Institute of Solid State Physics, Vienna University of Technology, Vienna, Austria
    • TU Vienna
    • Vienna Univ of Technology
    • Institute of Solid State Physics, TU Wien
    • Vienna University of Technology
    • Institute of Solid State Physics, Technischen Universita¨t (TU) Wien, Wiedner Hauptstraße 8-10, 1040 Vienna, Austria.