Direct Observation of Coherent Longitudinal and Shear Acoustic Phonons in TaAs Using Ultrafast X-Ray Diffraction - UFR SPM Sciences et Propriétés de la Matière Accéder directement au contenu
Article Dans Une Revue Physical Review Letters Année : 2022

Direct Observation of Coherent Longitudinal and Shear Acoustic Phonons in TaAs Using Ultrafast X-Ray Diffraction

Min-Cheol Lee
  • Fonction : Auteur correspondant

Résumé

Using femtosecond time-resolved x-ray diffraction, we investigated optically excited coherent acoustic phonons in the Weyl semimetal TaAs. The low symmetry of the (112) surface probed in our experiment enables the simultaneous excitation of longitudinal and shear acoustic modes, whose dispersion closely matches our simulations. We observed an asymmetry in the spectral line shape of the longitudinal mode that is notably absent from the shear mode, suggesting a time-dependent frequency chirp that is likely driven by photoinduced carrier diffusion. We argue on the basis of symmetry that these acoustic deformations can transiently alter the electronic structure near the Weyl points and support this with model calculations. Our study underscores the benefit of using off-axis crystal orientations when optically exciting acoustic deformations in topological semimetals, allowing one to transiently change their crystal and electronic structures.
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Dates et versions

hal-03687796 , version 1 (22-11-2022)

Identifiants

Citer

Min-Cheol Lee, N. Sirica, S. W. Teitelbaum, A. A Maznev, Thomas Pezeril, et al.. Direct Observation of Coherent Longitudinal and Shear Acoustic Phonons in TaAs Using Ultrafast X-Ray Diffraction. Physical Review Letters, 2022, 128 (15), pp.155301. ⟨10.1103/PhysRevLett.128.155301⟩. ⟨hal-03687796⟩
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