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

PhononCondensed matter physicsAnomaly (physics)PhysicsGrapheneBilayer grapheneBilayerLogarithmQuantum mechanicsChemistry

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Publication Info

Year
2008
Type
article
Volume
101
Issue
13
Pages
136804-136804
Citations
176
Access
Closed

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Cite This

Jun Yan, Erik Henriksen, Philip Kim et al. (2008). Observation of Anomalous Phonon Softening in Bilayer Graphene. Physical Review Letters , 101 (13) , 136804-136804. https://doi.org/10.1103/physrevlett.101.136804

Identifiers

DOI
10.1103/physrevlett.101.136804
PMID
18851480
arXiv
0712.3879

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Data completeness: 84%