The effective fine-structure constant of freestanding graphene measured in graphite

James P. Reed, Bruno Uchoa, Young Il Joe, Yu Gan, Diego Casa, Eduardo Fradkin, Peter Abbamonte

Research output: Contribution to journalArticlepeer-review


Electrons in graphene behave like Dirac fermions, permitting phenomena from high-energy physics to be studied in a solid-state setting. A key question is whether or not these fermions are critically influenced by Coulomb correlations. We performed inelastic x-ray scattering experiments on crystals of graphite and applied reconstruction algorithms to image the dynamical screening of charge in a freestanding graphene sheet. We found that the polarizability of the Dirac fermions is amplified by excitonic effects, improving screening of interactions between quasiparticles. The strength of interactions is characterized by a scale-dependent, effective fine-structure constant, αγ* (k, ω), the value of which approaches 0.14 ± 0.092 ∼ 1/7 at low energy and large distances. This value is substantially smaller than the nominal αγ = 2.2, suggesting that, on the whole, graphene is more weakly interacting than previously believed.

Original languageEnglish (US)
Pages (from-to)805-808
Number of pages4
Issue number6005
StatePublished - Nov 5 2010

ASJC Scopus subject areas

  • General


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