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Lecture Peter Abbamonte


03 June 2011 FWN-Building 5114.0004, Nijenborgh 4, 9747 AG, Groningen
Speaker: Prof. Dr. Peter Abbamonte
Affiliation: Department of Physics and Frederick Seitz Materials Research Laboratory,
University of Illinois, Urbana, USA
Title: The effective fine structure constant of graphene measure with attosecond x-ray imaging
Date: Fri Jun 3, 2011
Start: 11.00
Location: FWN-Building 5114.0004
Host: Thomas Palstra
Telephone: +31 50 363 4419


Electrons in graphene behave like Dirac fermions, permitting phenomena familiar 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. In this talk I will describe inelastic x-ray scattering experiments on crystals of graphite, which we have used, in conjunction with new reconstruction algorithms, to image the dynamical screening of charge in a freestanding, graphene sheet. We found that the polarizability of the Dirac fermions in graphene is enhanced by excitonic effects, improving the screening of interactions between renormalized quasiparticles. I will argue that the strength of interactions is characterized by a scale-dependent, effective fine structure constant, alpha(k,omega), whose value approaches ~1/7 at low energy and large distances. I will explain how to understand this result in the context of recent efforts to detect strongly correlated ground states in graphene and other Dirac systems.

*J. P. Reed, et al., Science 330, 805 (2010)

Last modified:22 October 2012 2.30 p.m.