New long-lived metastable state mediated by mode-selective electron-phonon coupling in 1<i>T</i>-TaSe<sub>2</sub>

ORAL

Abstract

Quantum materials represent one of the most promising frontiers in the quest for faster, lightweight, energy efficient technologies. However, their inherent complexity and rich phase landscape make them challenging to understand or manipulate in useful ways. Here we present a new ultrafast electron calorimetry technique that can systematically uncover new phases of quantum matter. Using time- and angle-resolved photoemission spectroscopy, we measure the dynamic electron temperature, band structure and heat capacity. We then show that this is a very sensitive probe of phase changes in materials, because electrons react very quickly, and moreover generally are the smallest component of the total heat capacity. This allows us to uncover a new long-lived metastable state in the charge density wave material 1T-TaSe2, that is distinct from all of the known equilibrium phases: it is characterized by a significantly reduced effective heat capacity that is only 30% of the normal value, due to selective electron-phonon coupling to a subset of phonon modes. As a result, significantly less energy is required to melt the charge order and transform the state of the material than under thermal equilibrium conditions.

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Presenters

  • Wenjing You

    • JILA, University of Colorado Boulder
    • Department of Physics and JILA, University of Colorado, Boulder
    • University of Colorado, Boulder

Authors

  • Wenjing You

    • JILA, University of Colorado Boulder
    • Department of Physics and JILA, University of Colorado, Boulder
    • University of Colorado, Boulder

  • Xun Shi

    • JILA, University of Colorado Boulder
    • Department of Physics and JILA, University of Colorado, Boulder
    • University of Colorado, Boulder

  • Yingchao Zhang

    • JILA, University of Colorado Boulder
    • Department of Physics and JILA, University of Colorado, Boulder
    • University of Colorado, Boulder

  • Zhensheng Tao

    • JILA, University of Colorado Boulder
    • Department of Physics and JILA, University of Colorado, Boulder
    • University of Colorado, Boulder

  • Peter Oppeneer

    • Uppsala University
    • Department of Physics and Astronomy, Uppsala University

  • Xianxin Wu

    • Institute for Theoretical Physics and Astrophysics, University of Wuerzburg
    • Physics, University of Wurzburg
    • Institute for Theoretical Physics and Astrophysics, Julius-Maximilians University of Wurzburg, Am Hubland, D-97074 Wurzburg, Germany
    • Institut für Theoretische Physik und Astrophysik, Julius-Maximilians-Universität Würzburg
    • Institute of Physics, Chinese Academy of Sciences
    • Univ of Wuerzburg
    • Institute for Theoretical Physics, University of Wuerzburg
    • Univ of Wurzburg

  • Ronny Thomale

    • Institute for Theoretical Physics and Astrophysics, University of Wuerzburg
    • University of Wurzburg
    • Institute for theoretical physics, University of Wuerzburg
    • Institute for Theoretical Physics and Astrophysics, University Wuerzburg
    • Institut für Theoretische Physik und Astrophysik, Julius-Maximilians-Universität Würzburg
    • Univ of Wuerzburg
    • Institute for Theoretical Physics and Astrophysics, University of Würzburg
    • Institute for Theoretical Physics, University of Wuerzburg
    • Univ of Wurzburg

  • Kai Rossnagel

    • Kiel University
    • Institute of Experimental and Applied Physics, Kiel University
    • Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany

  • Michael Bauer

    • Kiel University
    • Institute of Experimental and Applied Physics, Kiel University

  • Henry C Kapteyn

    • JILA, University of Colorado, Boulder
    • JILA, University of Colorado Boulder
    • Department of Physics and JILA, University of Colorado, Boulder
    • University of Colorado, Boulder / JILA
    • University of Colorado, Boulder

  • Margaret Mary Murnane

    • JILA, University of Colorado, Boulder
    • JILA, University of Colorado Boulder
    • Department of Physics and JILA, University of Colorado, Boulder
    • University of Colorado, Boulder / JILA
    • University of Colorado, Boulder