Measurement of the opptical conductivity of graphene

Kin Fai Mak, Matthew Y. Sfeir, Yang Wu, Chun Hung Lui, James A. Misewich, Tony F. Heinz

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Optical reflectivity and transmission measurements over photon energies between 0.2 and 1.2 eV were performed on single-crystal graphene samples on a SiO2 substrate. For photon energies above 0.5 eV, graphene yielded a spectrally flat optical absorbance of (2.3±0.2)%. This result is in agreement with a constant absorbance of πα, or a sheet conductivity of πe2/2h, predicted within a model of noninteracting massless Dirac fermions. This simple result breaks down at lower photon energies, where both spectral and sample-to-sample variations were observed. This "nonuniversal" behavior is explained by including the effects of doping and finite temperature, as well as contributions from intraband transitions.

Original languageEnglish (US)
Article number196405
JournalPhysical review letters
Issue number19
StatePublished - Nov 7 2008

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)


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