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Measurement of the optical conductivity of graphene.

TitleMeasurement of the optical conductivity of graphene.
Publication TypeJournal Article
Year of Publication2008
AuthorsMak, KFai, Sfeir, MY, Wu, Y, Lui, CHung, Misewich, JA, Heinz, TF
JournalPhys Rev Lett
Volume101
Issue19
Pagination196405
Date Published2008 Nov 07
ISSN0031-9007
Abstract

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 pialpha, or a sheet conductivity of pie2/2h, 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.

DOI10.1103/PhysRevLett.101.196405
Alternate JournalPhys. Rev. Lett.
PubMed ID19113291