Frequency splitting of intervalley phonons in graphene

K. Ziegler, E. Kogan

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


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.

Original languageEnglish
Article number36003
Issue number3
StatePublished - Aug 2011


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