Electron–electron interaction in high-quality epitaxial graphene

Weak localization is studied in two high-quality epitaxial graphene samples grown on silicon-faced 6H-SiC substrates. Following the methodology of Kozikov et al (2010 Phys. Rev. B 82 075424), we measured the temperature dependence of carrier conductivity at zero and low magnetic (B) fields. In both samples, a logarithmic temperature dependence of the carrier conductivity was observed at B = 0 and its amplitude was larger than predicted by a single-particle model, suggesting that electron–electron interaction plays an important role in electron transport in epitaxial graphene films. The ground state of a two-dimensional electron system (2DES) at T = 0 has been researched intensively for many years. In particular, electron transport properties in the presence of electron–electron (e–e) interactions have been at the center of recent research [1]. With the arrival of graphene [2–6], new ground states induced by the combination of e–e interactions and massless Dirac fermions have been proposed4. Indeed, the 2DES in graphene may represent a novel two-dimensional (2D) Fermi liquid with unusual e–e interaction physics. Recent observations of the fractional quantum Hall effect at Landau level filling ν = 1/3 [8–10], manybody originated ν =±1 states [11], the e–e interaction-induced shift in the cyclotron resonance 3 Author to whom any correspondence should be addressed. 4 For a recent review on e–e interactions in graphene, see, for example, [7]. New Journal of Physics 13 (2011) 113005 1367-2630/11/113005+07$33.00 © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft