Anomalous Exciton Condensation in Graphene Bilayers
Abstract
In ordinary semiconductor bilayers, exciton condensates appear at total Landaulevel filling factor ν_{T}=1. We predict that similar states will occur in Bernal stacked graphene bilayers at many nonzero integer filling factors. For ν_{T}=3, 1 we find that the superfluid density of the exciton condensate vanishes and that a finitetemperature fluctuationinduced first order isotropicsmectic phase transition occurs when the layer densities are not balanced. These anomalous properties of bilayer graphene exciton condensates are due to the degeneracy of Landau levels with n=0 and n=1 orbital character.
 Publication:

Physical Review Letters
 Pub Date:
 March 2010
 DOI:
 10.1103/PhysRevLett.104.096802
 arXiv:
 arXiv:0909.1502
 Bibcode:
 2010PhRvL.104i6802B
 Keywords:

 73.43.f;
 71.35.Ji;
 73.21.b;
 Quantum Hall effects;
 Excitons in magnetic fields;
 magnetoexcitons;
 Electron states and collective excitations in multilayers quantum wells mesoscopic and nanoscale systems;
 Condensed Matter  Mesoscale and Nanoscale Physics
 EPrint:
 4 pages, 1 figure