Novel photoinduced charge density wave state and periodic lattice distortion in 1<i>T</i>-TaSe<sub>2</sub>

ORAL

Abstract

The amplitude mode in a charge density wave (CDW) material is the collective modulation of the relevant periodic lattice distortion (PLD). Here we use a femtosecond laser pulse to displacively excite the coherent amplitude mode in the CDW material 1T-TaSe2. We then use time- and angle-resolved photoemission to track the dynamic evolution of the amplitude mode and electronic band structure – and in particular, the position and the width of the Ta 5d band. At sufficiently high fluences, and within a half-cycle of the amplitude mode oscillation, the PLD of 1T-TaSe2 first relaxes to the position of the normal state, before overshooting to form an inverted CDW transient state. Moreover, the band width is maximum for the normal state, while it is reduced for both the ground CDW state and the inverted CDW state. Another important observation is that this inverted CDW state has larger density of states at the Fermi level than the normal state. Our observations are consistent with both density functional theory (DFT) and tight binding calculations. Our results show the possibility of using light to generate unique lattice distortions and electron correlations via ultrafast coherent phonon excitation.

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Presenters

  • Yingchao Zhang

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

Authors

  • Yingchao Zhang

    • 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

  • Wenjing You

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

  • Zhensheng Tao

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

  • Yigui Zhong

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

  • Peter Oppeneer

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

  • Michael Bauer

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

  • Kai Rossnagel

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

  • Henry Kapteyn

    • JILA, University of Colorado Boulder
    • Department of Physics and JILA, University of Colorado, Boulder
    • STROBE and JILA, University of Colorado, Boulder
    • JILA and Department of Physics, University of Colorado, Boulder
    • STROBE and JILA, University of Colorado and NIST
    • Physics, JILA/University of Colorado Boulder
    • JILA
    • University of Colorado, Boulder
    • Physics and JILA, CU Boulder
    • JILA, University of Colorado, Boulder

  • Margaret Murnane

    • JILA, University of Colorado Boulder
    • Department of Physics and JILA, University of Colorado, Boulder
    • STROBE and JILA, University of Colorado, Boulder
    • STROBE and JILA, University of Colorado and NIST
    • JILA
    • University of Colorado, Boulder
    • Physics and JILA, CU Boulder
    • University of Colorado
    • JILA, University of Colorado, Boulder