Observation of Anomalous Phonon Softening in Bilayer Graphene
- 25 September 2008
- journal article
- Published by American Physical Society (APS) in Physical Review Letters
- Vol. 101 (13), 136804
- https://doi.org/10.1103/physrevlett.101.136804
Abstract
The interaction of electron-hole pairs with lattice vibrations exhibits a wealth of intriguing physical phenomena such as the renowned Kohn anomaly. Here we report the observation in bilayer graphene of an unusual phonon softening that provides the first experimental proof for another type of phonon anomaly. Similar to the Kohn anomaly, which is a logarithmic singularity in the phonon group velocity [W. Kohn, Phys. Rev. Lett. 2, 393 (1959)], the observed phonon anomaly exhibits a logarithmic singularity in the optical-phonon energy. Arising from a resonant electron-phonon coupling effect, the anomaly was also expected, albeit not observed, in monolayer graphene. We propose an explanation for why it is easier to observe in bilayer samples.Keywords
This publication has 26 references indexed in Scilit:
- Interplay of Coulomb and electron-phonon interactions in graphenePhysical Review B, 2008
- Measurement of Scattering Rate and Minimum Conductivity in GraphenePhysical Review Letters, 2007
- A self-consistent theory for graphene transportProceedings of the National Academy of Sciences, 2007
- Probing zone-boundary optical phonons in doped graphenePhysical Review B, 2007
- Energy Band-Gap Engineering of Graphene NanoribbonsPhysical Review Letters, 2007
- Electric Field Effect Tuning of Electron-Phonon Coupling in GraphenePhysical Review Letters, 2007
- The rise of grapheneNature Materials, 2007
- Electron-phonon coupling and Raman spectroscopy in graphenePhysical Review B, 2007
- Effects of interband excitations on Raman phonons in heavily dopedPhysical Review B, 1978
- Effect of Carrier Concentration on the Raman Frequencies of Si and GePhysical Review B, 1972