Nanoscale Charge-order Dynamics in Stripe-phase Nickelates Probed via Ultrafast THz Spectroscopy

ORAL

Abstract

Here we report ultrafast optical pump-THz probe spectroscopy of the model stripe-ordered system La$_{\mathrm{1.75}}$Sr$_{\mathrm{0.25}}$NiO$_{\mathrm{4}}$. Ultrafast experiments in the multi-THz spectral range show strong THz reflectivity variations around the phonon bending mode frequency ($\approx $11 THz). At low temperatures this phonon mode exhibits a splitting directly related to the formation of long-range stripe-order, while the background conductivity is reminiscent of the opening of the mid-IR pseudogap due to charge localization. The transient THz probe therefore captures both the electronic and structural dynamics in a single light pulse. The results reveal the dynamical interplay between charge localization and the bending mode folding, providing insight in the emergence of nanoscale charge-order in complex oxides.

*This work was supported by the US Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering.

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Authors

  • Giacomo Coslovich

    • Lawrence Berkeley National Laboratory

  • Sascha Behl

    • Lawrence Berkeley National Laboratory

  • Bernhard Huber

    • Lawrence Berkeley National Laboratory

  • Wei-Sheng Lee

    • SIMES, SLAC National Accelerator Laboratory, Stanford University

  • Zhi-Xun Shen

    • SIMES, SLAC National Accelerator Laboratory, Stanford University

  • Takao Sasagawa

    • Tokyo Institute of Technology

  • Hans A. Bechtel

    • Lawrence Berkeley National Laboratory

  • Michael C. Martin

    • Lawrence Berkeley National Laboratory

  • Robert A. Kaindl

    • Lawrence Berkeley National Laboratory