Structural Phase Transformations in Photoexcited Transition Metal Chalcogenide Monolayers Studied Using Combined Pump-Probe Experiments and Non-Adiabatic Molecular Dynamics Simulations

ORAL

Abstract

Optical control of structural phases in two dimensional chalcogenides is a promising route for precise functionalization of these materials for electronic, optical and catalytic applications. In this study, we use ab initio time dependent density functional theory simulations supported by ultrafast electron diffraction measurements to understand the electronic structure of electronically-excited MoTe2 crystals as well as the resulting atomic dynamics responsible for transformation between the H and T’ crystal structures. Specifically, we identify a nesting of the excited-state Fermi surface that leads to softening of phonon modes at the Brillouin zone boundary. This modulation of the ionic potential energy surface exposes a low activation-energy-barrier pathway for the H-T’ phase transformation in this family of materials. This example of excitation-driven phase transformation has important advantages over other reported phase transformation mechanisms that rely on thermal and chemical driving forces or electron-doping.

*This work was supported as part of the Computational Materials Sciences Program funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, under Award Number DE-SC00014607.

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Presenters

  • Aravind Krishnamoorthy

    • Physics & Astronomy, University of Southern California
    • Univ of Southern California
    • Physics, University of Southern California
    • University of Southern California

Authors

  • Aravind Krishnamoorthy

    • Physics & Astronomy, University of Southern California
    • Univ of Southern California
    • Physics, University of Southern California
    • University of Southern California

  • Ming-Fu Lin

    • SLAC National Accelerator Laboratory
    • SLAC - Natl Accelerator Lab

  • Clemens Weninger

    • SLAC National Accelerator Laboratory
    • SLAC - Natl Accelerator Lab

  • Rajiv Kalia

    • Univ of Southern California
    • Physics & Astronomy, University of Southern California
    • University of Southern California
    • Mork Family Department of Chemical Engineering and Materials Science, Univ of Southern California
    • Collaboratory of Advanced Computing and Simulations, Univ of Southern California
    • Collaboratory for Advanced Computing and Simulations, University of Southern California
    • Physics, University of Southern California

  • Aiichiro Nakano

    • Univ of Southern California
    • Physics & Astronomy, University of Southern California
    • University of Southern California
    • Mork Family Department of Chemical Engineering and Materials Science, Univ of Southern California
    • Collaboratory of Advanced Computing and Simulations, Univ of Southern California
    • Physics, University of Southern California

  • Fuyuki Shimojo

    • Physics, Kumamoto University
    • Kumamoto University
    • Department of Physics, Kumamoto University

  • Uwe Bergmann

    • SLAC National Accelerator Laboratory
    • SLAC - Natl Accelerator Lab

  • Priya Vashishta

    • Univ of Southern California
    • Physics & Astronomy, University of Southern California
    • University of Southern California
    • Mork Family Department of Chemical Engineering and Materials Science, Univ of Southern California
    • Collaboratory of Advanced Computing and Simulations, Univ of Southern California
    • Collaboratory for Advanced Computing and Simulations, University of Southern California
    • Physics, University of Southern California