Strong Charge-Transfer Excitonic Effects and the Bose-Einstein Exciton Condensate in Graphane

Claudio Attaccalite (1) , Angel Rubio (2) , Cudazzo Pierluigi (2) , Ilya V. Tokatly (2)

1 NEEL - TMC - Théorie de la Matière Condensée
2 nanobio - Nano-Bio Spectroscopy group

Using first principles many-body theory methods (GW+Bethe-Salpeter equation) we demonstrate that the optical properties of graphane are dominated by localized charge-transfer excitations governed by enhanced electron correlations in a two-dimensional dielectric medium. Strong electron-hole interaction leads to the appearance of small radius bound excitons with spatially separated electron and hole, which are localized out of plane and in plane, respectively. The presence of such bound excitons opens the path towards an excitonic Bose-Einstein condensate in graphane that can be observed experimentally.

Domaines: Science des matériaux [cond-mat.mtrl-sci]

Claudio Attaccalite, Angel Rubio, Cudazzo Pierluigi, Ilya V. Tokatly. Strong Charge-Transfer Excitonic Effects and the Bose-Einstein Exciton Condensate in Graphane. Physical Review Letters, 2010, 104, pp.226804. ⟨10.1103/PhysRevLett.104.226804⟩. ⟨hal-00695023⟩