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arXiv · 1012.3162

Frequency splitting of intervalley phonons in graphene

K. Ziegler·E. Kogan
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Abstract

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.

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K. Ziegler, E. Kogan. 2010-12-14. Frequency splitting of intervalley phonons in graphene. https://doi.org/10.1209/0295-5075%2F95%2F36003

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