Observation of Anomalous Phonon Softening in Bilayer Graphene

Jun Yan, Erik A. Henriksen, Philip Kim, and Aron Pinczuk
Phys. Rev. Lett. 101, 136804 – Published 25 September 2008

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.

  • Figure
  • Figure
  • Figure
  • Figure
  • Received 14 April 2008

DOI:https://doi.org/10.1103/PhysRevLett.101.136804

©2008 American Physical Society

Authors & Affiliations

Jun Yan1,*, Erik A. Henriksen1, Philip Kim1, and Aron Pinczuk1,2

  • 1Department of Physics, Columbia University, New York, New York 10027, USA
  • 2Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027, USA

  • *jy2115@columbia.edu

Article Text (Subscription Required)

Click to Expand

References (Subscription Required)

Click to Expand
Issue

Vol. 101, Iss. 13 — 26 September 2008

Reuse & Permissions
Access Options

Authorization Required


×
×

Images

×

Sign up to receive regular email alerts from Physical Review Letters

Log In

Cancel
×

Search


Article Lookup

Paste a citation or DOI

Enter a citation
×