Direct observation of acoustic phonon oscillations in the Weyl semimetal TaAs using ultrafast x-ray diffraction

POSTER

Abstract

In the Weyl semimetal TaAs, we investigated optically excited acoustic phonon oscillations using time-resolved X-ray diffraction. The unique surface orientation (112) of the TaAs crystal enabled the simultaneous observation of longitudinal and shear acoustic modes, whose dispersion closely matches our simulations. The long penetration depth and high temporal resolution of femtosecond X-ray pulses allow us to observe an asymmetric lineshape of the longitudinal mode, which is absent from the shear mode. We attribute this spectral asymmetry to a time-dependent frequency chirp resulting from the thermal diffusion of photoinduced carriers. Our study also highlights the benefit of using off-axis crystal orientations in topological materials to optically excite shear deformations, allowing one to transiently control crystal structures of these materials and potentially their topological properties.

Presenters

  • Min-Cheol Lee

    • Los Alamos National Laboratory
    • Center for Integrated Nanotechnologies, Los Alamos National Laboratory

Authors

  • Min-Cheol Lee

    • Los Alamos National Laboratory
    • Center for Integrated Nanotechnologies, Los Alamos National Laboratory

  • Nicholas Sirica

    • Los Alamos National Laboratory
    • CINT, Los Alamos National Lab

  • Samuel Teitelbaum

    • physics, arizona state university
    • Arizona State University

  • Alexei Maznev

    • Massachusetts Institute of Technology

  • Thomas Pezeril

    • Massachusetts Institute of Technology

  • Roxanne Tutchton

    • Los Alamos National Laboratory
    • Center for Integrated Nanotechnologies, Los Alamos National Laboratory

  • Viktor Krapivin

    • SLAC National Accelerator Laboratory

  • Gilberto de la Pena

    • Stanford Univ
    • SLAC National Accelerator Laboratory

  • Yijing Huang

    • Stanford Univ
    • SLAC National Accelerator Laboratory

  • Jiaojian Shi

    • Massachusetts Institute of Technology

  • Jian-Xin Zhu

    • Los Alamos Natl Lab
    • Los Alamos National Laboratory
    • Theoretical Division/Center for Integrated Nanotechnology, Los Alamos National Laboratory
    • Theoretical Division and Center for Integrated Nanotechnologies, Los Alamos National Lab
    • Center for Integrated Nanotechnologies, Los Alamos National Laboratory

  • Dmitry Yarotski

    • Los Alamos National Laboratory
    • CINT, Los Alamos National Lab
    • Department of Physics, Massachusetts Institute of Technology
    • Center for Integrated Nanotechnologies, Los Alamos National Laboratory

  • Xianggang Qiu

    • Chinese Academy of Sciences

  • Keith Adam Nelson

    • Massachusetts Institute of Technology

  • Mariano Trigo

    • SLAC - Natl Accelerator Lab
    • Stanford Univ
    • SLAC National Accelerator Laboratory

  • David A Reis

    • Stanford Univ
    • SLAC National Accelerator Laboratory

  • Rohit P Prasankumar

    • Los Alamos National Laboratory
    • CINT, Los Alamos National Lab
    • Center for Integrated Nanotechnologies, Los Alamos National Laboratory