Pump-probe Nano-spectroscopy of Mott Insulating Ca<sub>2</sub>RuO<sub>4</sub>

ORAL

Abstract

Ca2RuO4 is a Mott Insulator that exhibits a temperature-induced insulator to metal transition occurring slightly above room temperature. Further, Ca2RuO4 exhibits a current-driven IMT at room temperature and current-induced diamagnetism below 50K. These discoveries, particularly the latter, imply that the application of current can expose a previously hidden state in Ca2RuO4. Motivated by the current induced transition, we conducted nanoscale pump-probe measurements to explore the phase diagram further. In our experiments, we study both the static and photo-induced response with nano-FTIR measurements to interrogate the dynamics of the spectral response throughout the mid-IR. The static spectra reveal a large phonon resonance of the in-plane stretching mode of the Ru-O bonds in the insulating state, while the metallic state demonstrates a flat, Drude like response. The photo-induced spectra reveal an initial suppression of the phonon mode and a noticeable increase in the Drude response at later times. We interpret the response as an initial injection of charge carriers that screen the phonon mode while their thermalization at later times leads to the Drude-like response.

*NDSEG Fellowship

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Presenters

  • Rocco Vitalone

    • Columbia University, The Department of Physics
    • Physics, Columbia University

Authors

  • Rocco Vitalone

    • Columbia University, The Department of Physics
    • Physics, Columbia University

  • Aaron Sternbach

    • Columbia Univ
    • Department of Physics, Columbia University
    • Physics, Columbia University

  • Ben Foutty

    • Physics, Columbia University

  • Alexander McLeod

    • Columbia Univ
    • Columbia University
    • Physics, Columbia University

  • Chanchal Sow

    • Department of Physics, Graduate School of Science, Kyoto University
    • Physics, Kyoto Univeristy

  • Fumihiko Nakamura

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

  • Yoshiteru Maeno

    • Department of Physics, Kyoto University
    • Kyoto Univ.
    • Kyoto University
    • Kyoto Univ
    • Department of Physics, Graduate School of Science, Kyoto University
    • Department of Physics, Kyoto University, Japan
    • Physics, Kyoto Univeristy
    • Physics, Kyoto University
    • Department of Physics, Graduate School of Science, Kyoto University, Japan

  • Abhay Pasupathy

    • Columbia University
    • Physics Department, Columbia University
    • Columbia Univ
    • Department of Physics, Columbia University, New York, New York 10027, USA
    • Physics, Columbia University
    • Department of Physics, Columbia University

  • Dmitri Basov

    • Columbia University, The Department of Physics
    • Columbia University
    • Physics, Columbia University
    • Columbia Univ
    • Department of Physics, Columbia University