期刊
SCIENCE
卷 330, 期 6005, 页码 805-808出版社
AMER ASSOC ADVANCEMENT SCIENCE
DOI: 10.1126/science.1190920
关键词
-
资金
- U.S. Department of Energy through the Frederick Seitz Materials Research Laboratory [DE-FG02-07ER46459, DE-FG02-07ER46453, DEAC02-06CH11357]
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 similar to 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.
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