Ultrafast electron calorimetry to uncover new transient states in charge density wave and magnetic materials

ORAL

Abstract

Understanding and harnessing phase transitions in a wide range of quantum materials remains a great challenge. The strongly coupled interactions between the charges, spins and lattice often make it challenging to unambiguously uncover the underlying mechanisms. Here we present a new ultrafast electron calorimetry technique to map the laser-driven phase space of materials. It relies on the small mass and heat capacity of the electrons, which means that they can react very quickly to any phase changes in a material. Specifically, we use time- and angle-resolved photoemission spectroscopy to systematically measure the band structure, electron temperature and heat capacity as a function of both time delay and laser fluence. First, we find a new metastable state in the charge density wave material 1T-TaSe2, which is characterized by a significantly reduced effective heat capacity. Our results also reveal new manifestations of the electron-phonon coupling in the dynamics of both the electron and phonon bathes. Second, we uncover a highly-excited spin state that launches the ultrafast magnetic phase transition in Ni. Finally, we note that our approach is general, and can be used to uncover the presence of hidden phases in other materials.

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Presenters

  • Xun Shi

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

Authors

  • Xun Shi

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

  • Wenjing You

    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

  • Phoebe Tengdin

    Physics, University of Colorado, JILA, University of Colorado Boulder, University of Colorado, Boulder / JILA, JILA, University of Colorado, Boulder

  • Cong Chen

    JILA, University of Colorado Boulder

  • Dmitriy Zusin

    Physics, University of Colorado, JILA, University of Colorado Boulder, University of Colorado, Boulder / JILA, JILA, University of Colorado, Boulder

  • Christian Gentry

    JILA, University of Colorado Boulder, University of Colorado, Boulder / JILA, JILA, University of Colorado, Boulder

  • Adam Z Blonsky

    JILA, University of Colorado Boulder, JILA, University of Colorado, Boulder

  • Mark Keller

    National Institute of Standards and Technology Boulder, NIST - Boulder

  • 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