Collective modes in Sr<sub>2</sub>RuO<sub>4</sub> measured with momentum-resolved EELS (M-EELS)

ORAL

Abstract

Measurements of the charge susceptibility χ(q,ω) of the high-Tc cuprate Bi-2212 using Momentum-resolved inelastic electron scattering (M-EELS) have shown that bad-metallic behavior can be characterized by a continuum of non-propagating density fluctuations, in stark contrast to the plasmons of simple metals [1]. Here, we report on M-EELS measurements of Sr2RuO4, a bad metal which crosses over to a Fermi Liquid at T=40K. Like Bi-2212, we find that the bad metal phase of Sr2RuO4 exhibits a continuum of density fluctuations. However, below 40K, spectral weight is redistributed to form a plasmon-like excitation around 1.4 eV. Surprisingly, we also discover a coherent low-energy (sub-80meV) 2D acoustic plasmon in the bad metal phase, whose velocity is strongly renormalized from 0.7 to 0.4eV Å below the Fermi liquid crossover, indicating a coupled 2D Fermi Liquid and 3D bad metal in a single solid. We will contrast this coupled system to a closely related ruthenate, the Mott-insulator Ca2RuO4.

[1] M. Mitrano, A. A. Husain, et al. PNAS 115 (21) 5392-5396 (2018)

*This work was supported by the Gordon and Betty Moore Foundation's EPiQS Initiative through Grant GBMF-4542. An early prototype of the M-EELS instrument was supported by the DOE CES under award DE-AC02-98CH10886.

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Presenters

  • Ali Husain

    • University of Illinois at Urbana-Champaign
    • Department of Physics and Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign
    • Physics, University of Illinois at Urbana-Champaign

Authors

  • Ali Husain

    • University of Illinois at Urbana-Champaign
    • Department of Physics and Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign
    • Physics, University of Illinois at Urbana-Champaign

  • Matteo Mitrano

    • University of Illinois at Urbana-Champaign
    • Department of Physics and Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign
    • Physics, University of Illinois at Urbana-Champaign

  • Melinda Rak

    • University of Illinois at Urbana-Champaign
    • Department of Physics and Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign

  • Samantha Rubeck

    • University of Illinois at Urbana-Champaign
    • Department of Physics and Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign

  • Fumihiko Nakamura

    • Department of Education and Creation Engineering, Kurume Institute of Technology

  • Chanchal Sow

    • Department of Physics, Graduate School of Science, Kyoto University
    • Department of Physics, Kyoto University, Kyoto 606-8502, Japan

  • Yoshiteru Maeno

    • Department of Physics, Kyoto University
    • Dept. of Physics, Kyoto University
    • Department of Physics, Graduate School of Science, Kyoto University, Kyoto, Japan
    • Kyoto University
    • Department of Physics, Graduate School of Science, Kyoto University
    • Department of Physics, Kyoto University, Kyoto 606-8502, Japan
    • Department of Physics, Kyoto University, Japan

  • Peter Abbamonte

    • University of Illinois, Urbana-Champaign
    • University of Illinois at Urbana-Champaign
    • Department of Physics and Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign