Abstract
Free-standing exfoliated monolayer graphene is an ultrathin flexible membrane, which exhibits out-of-plane deformation or corrugation. In this paper, a technique is described to measure the band structure of such free-standing graphene by angle-resolved photoemission. Our results show that photoelectron coherence is limited by the crystal corrugation. However, by combining surface morphology measurements of the graphene roughness with angle-resolved photoemission, energy-dependent quasiparticle lifetime and band-structure measurements can be extracted. Our measurements rely on our development of an analytical formulation for relating the crystal corrugation to the photoemission linewidth. Our angle-resolved photoemission spectroscopy measurements show that, despite significant deviation from planarity of the crystal, the electronic structure of exfoliated suspended graphene is nearly that of ideal, undoped graphene; we measure the Dirac point to be within 25 meV of . Further, we show that suspended graphene behaves as a marginal Fermi liquid, with a quasiparticle lifetime that scales as ; comparison with other graphene and graphite data is discussed.
1 More- Received 5 April 2011
DOI:https://doi.org/10.1103/PhysRevB.84.115401
©2011 American Physical Society
Synopsis
Shining light on corrugated graphene
Published 1 September 2011
Photoemission measurements detect the effects of local curvature on the band structure of suspended graphene.
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