Femtosecond electron imaging of defect-modulated phonon dynamics

Daniel R. Cremons, Dayne A. Plemmons, David J. Flannigan

Research output: Contribution to journalArticle

36 Scopus citations

Abstract

Precise manipulation and control of coherent lattice oscillations via nanostructuring and phonon-wave interference has the potential to significantly impact a broad array of technologies and research areas. Resolving the dynamics of individual phonons in defect-laden materials presents an enormous challenge, however, owing to the interdependent nanoscale and ultrafast spatiotemporal scales. Here we report direct, real-space imaging of the emergence and evolution of acoustic phonons at individual defects in crystalline WSe 2 and Ge. Via bright-field imaging with an ultrafast electron microscope, we are able to image the sub-picosecond nucleation and the launch of wavefronts at step edges and resolve dispersion behaviours during propagation and scattering. We discover that the appearance of speed-of-sound (for example, 6 nm ps-1) wavefronts are influenced by spatially varying nanoscale strain fields, taking on the appearance of static bend contours during propagation. These observations provide unprecedented insight into the roles played by individual atomic and nanoscale features on acoustic-phonon dynamics.

Original languageEnglish (US)
Article number11230
JournalNature communications
Volume7
DOIs
StatePublished - Apr 15 2016

How much support was provided by MRSEC?

  • Primary

Reporting period for MRSEC

  • Period 3

PubMed: MeSH publication types

  • Journal Article
  • Research Support, Non-U.S. Gov't

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  • Projects

    University of Minnesota MRSEC (DMR-1420013)

    Lodge, T. P.

    11/1/1410/31/20

    Project: Research project

    MRSEC SEED Projects

    11/1/14 → …

    Project: Research project

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