Ultrafast investigation of photo-excited carrier-lattice dynamics in PbTe using Fourier-transform inelastic X-ray scattering

ORAL

Abstract

We report with fine temporal and momentum resolution non-equilibrium electron-phonon and phonon-phonon dynamics in the widely-used thermoelectric material PbTe. The measurements are made possible by both the intense, ultrafast X-ray pulses of the Linac Coherent Light Source instrument and the recently developed Fourier-transform inelastic X-ray scattering (FT-IXS) technique. We demonstrate experimentally the various effects of impulsive optical photo-excitation on the lattice dynamics of the material as carriers are dramatically redistributed in the system. Specifically, coupled two-phonon states are excited throughout various Brillouin zones and possible plasmon-phonon modes are observed very near zone center. Coupled with calculations from density functional theory (DFT), an analysis of these photo-excited modes yields new insight into the origins of the incipient ferroelectricity and zone center anomalies noted in past measurements on PbTe.

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Authors

  • Mason Jiang

    • PULSE Institute, Stanford University

  • Crystal Bray

    • PULSE Institute, Stanford University

  • Jesse Clark

    • PULSE Institute, Stanford University

  • Tom Henighan

    • PULSE Institute, Stanford University

  • Mike Kozina

    • PULSE Institute, Stanford University

  • Aaron Lindenberg

    • PULSE Institute, Stanford University

  • Mariano Trigo

    • PULSE Institute, Stanford University

  • Peter Zalden

    • PULSE Institute, Stanford University

  • David Reis

    • PULSE Institute, Stanford University

  • Matthieu Chollet

    • LCLS, SLAC National Accelerator Laboratory

  • James Glownia

    • LCLS, SLAC National Accelerator Laboratory

  • Matthias Hoffmann

    • LCLS, SLAC National Accelerator Laboratory

  • Diling Zhu

    • LCLS, SLAC National Accelerator Laboratory

  • Olivier Delaire

    • Oak Ridge National Laboratory

  • Andrew May

    • Oak Ridge National Laboratory

  • Brian Sales

    • Oak Ridge National Laboratory

  • Stephen Fahy

    • Tyndall National Institute

  • Eamonn Murray

    • Tyndall National Institute

  • Ivana Savic

    • Tyndall National Institute