Coherent Lattice Wobbling and Out-of-Phase Intensity Oscillations of Friedel Pairs Observed by Ultrafast Electron Diffraction

Qingkai Qian, Xiaozhe Shen, Duan Luo, Lanxin Jia, Michael Kozina, Renkai Li, Ming Fu Lin, Alexander H. Reid, Stephen Weathersby, Suji Park, Jie Yang, Yu Zhou, Kunyan Zhang, Xijie Wang, Shengxi Huang

Research output: Contribution to journalArticlepeer-review

Abstract

The inspection of Friedel's law in ultrafast electron diffraction (UED) is important to gain a comprehensive understanding of material atomic structure and its dynamic response. Here, monoclinic gallium telluride (GaTe), as a low-symmetry, layered crystal in contrast to many other 2D materials, is investigated by mega-electronvolt UED. Strong out-of-phase oscillations of Bragg peak intensities are observed for Friedel pairs, which does not obey Friedel's law. As evidenced by the preserved mirror symmetry and supported by both kinematic and dynamic scattering simulations, the intensity oscillations are provoked by the lowest-order longitudinal acoustic breathing phonon. Our results provide a generalized understanding of Friedel's law in UED and demonstrate that by designed misalignment of surface normal and primitive lattice vectors, coherent lattice wobbling and effective shear strain can be generated in crystal films by laser pulse excitation, which is otherwise hard to achieve and can be further utilized to dynamically tune and switch material properties.

Original languageEnglish (US)
Pages (from-to)8449-8458
Number of pages10
JournalACS nano
Volume14
Issue number7
DOIs
StatePublished - Jul 28 2020

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Engineering(all)
  • Physics and Astronomy(all)

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