Publication Date:
2010-11-06
Description:
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, alpha(g)* (k,omega), 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 alpha(g) = 2.2, suggesting that, on the whole, graphene is more weakly interacting than previously believed.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Reed, James P -- Uchoa, Bruno -- Joe, Young Il -- Gan, Yu -- Casa, Diego -- Fradkin, Eduardo -- Abbamonte, Peter -- New York, N.Y. -- Science. 2010 Nov 5;330(6005):805-8. doi: 10.1126/science.1190920.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Physics and Frederick Seitz Materials Research Laboratory, University of Illinois, Urbana, IL 61801, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/21051634" target="_blank"〉PubMed〈/a〉
Print ISSN:
0036-8075
Electronic ISSN:
1095-9203
Topics:
Biology
,
Chemistry and Pharmacology
,
Computer Science
,
Medicine
,
Natural Sciences in General
,
Physics
Permalink