Dielectric Constant and Screened Interactions in AA Stacked Bilayer Graphene
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AA stacked bilayer graphene has a band structure consisting of two Dirac cones, bonding and antibonding, displaced in energies. In absence of interaction between electrons, the system is metallic and the Fermi surface consists of circles in the bonding and antibonding bands which coincides exactly. In presence of interaction between electrons the system is unstable to the condensation of bonding-like electrons and antibonding-like holes. The properties and the critical temperature of this gapped phase depends strongly on the screening on the interaction between pairs at large distances. In this work we study the polarizability and the intra and interlayer screened Coulomb interactions of a AA-stacked bilayer graphene for different energy gaps in the spectrum. We obtain that the existence of a gap suppress the screening at small wavevectors. Our results indcates the importance of a self-consistent treatment of the screening in the study of gapped phases in AA stacked bilayer graphene.
KeywordsRandom Phase Approximation Dirac Point Monolayer Graphene Bilayer Graphene Dirac Cone
The author wants to thank Prof. H.A.Fertig for enlightening discussions. Funding for the work described here was provided by MICINN-SPAIN via grant No. FIS2009-08744.
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