Unusual ultra-low-frequency fluctuations in freestanding graphene

Intrinsic ripples in freestanding graphene have been exceedingly difficult to study. Individual ripple geometry was recently imaged using scanning tunnelling microscopy, but these measurements are limited to static configurations. Thermally-activated flexural phonon modes should generate dynamic cha...

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Bibliographic Details
Published in:Nature communications 2014-04, Vol.5 (1), p.3720-3720
Main Authors: Xu, P., Neek-Amal, M., Barber, S. D., Schoelz, J. K., Ackerman, M. L., Thibado, P. M., Sadeghi, A., Peeters, F. M.
Format: Article
Language:English
Subjects:
639/301/1034
639/766/25
639/925/918
Elasticity
Graphite - chemistry
Humanities and Social Sciences
Microscopy, Scanning Tunneling - methods
Models, Chemical
multidisciplinary
Nanotechnology - methods
Phonons
Science
Science (multidisciplinary)
Temperature
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Summary:Intrinsic ripples in freestanding graphene have been exceedingly difficult to study. Individual ripple geometry was recently imaged using scanning tunnelling microscopy, but these measurements are limited to static configurations. Thermally-activated flexural phonon modes should generate dynamic changes in curvature. Here we show how to track the vertical movement of a one-square-angstrom region of freestanding graphene using scanning tunnelling microscopy, thereby allowing measurement of the out-of-plane time trajectory and fluctuations over long time periods. We also present a model from elasticity theory to explain the very-low-frequency oscillations. Unexpectedly, we sometimes detect a sudden colossal jump, which we interpret as due to mirror buckling. This innovative technique provides a much needed atomic-scale probe for the time-dependent behaviours of intrinsic ripples. The discovery of this novel progenitor represents a fundamental advance in the use of scanning tunnelling microscopy, which together with the application of a thermal load provides a low-frequency nano-resonator. Measuring local intrinsic ripples in freestanding graphene is difficult, and typically methods are limited to static configurations. Here the authors describe a scanning tunnelling microscope approach that focuses on areas of one square angstrom, giving detailed measurements over long time periods.
ISSN:2041-1723
DOI:10.1038/ncomms4720