Issue |
EPL
Volume 95, Number 3, August 2011
|
|
---|---|---|
Article Number | 36003 | |
Number of page(s) | 5 | |
Section | Condensed Matter: Structural, Mechanical and Thermal Properties | |
DOI | https://doi.org/10.1209/0295-5075/95/36003 | |
Published online | 19 July 2011 |
Frequency splitting of intervalley phonons in graphene
1
Institut für Physik, Universität Augsburg - 86135 Augsburg, Germany, EU
2
Department of Physics, Bar-Ilan University - Ramat Gan 52900, Israel
a
klaus.ziegler@physik.uni-augsburg.de
Received:
30
May
2011
Accepted:
18
June
2011
We study the thermal distribution of intervalley phonons in a graphene sheet. These phonons have two components with the same frequency. The degeneracy of the two modes is preserved by weak electron-phonon coupling. A sufficiently strong electron-phonon coupling, however, can result in a splitting into an optical and an acoustic phonon branch, which creates a fluctuating gap in the electronic spectrum. We describe these effects by treating the phonon distribution within a saddle-point approximation. Fluctuations around the saddle point indicate a Berezinskii-Kosterlitz-Thouless transition of the acoustic branch. This transition might be observable in the polarization of Raman scattered light.
PACS: 63.22.Rc – Phonons in graphene / 72.80.Vp – Electronic transport in graphene / 72.10.Di – Scattering by phonons, magnons, and other nonlocalized excitations
© EPLA, 2011
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