Real-space pairing through charge transfer excitons in High-Tc cuprates

Michel Pouchard (1) , Jean-Pierre Doumerc (1) , Antoine Villesuzanne (1)

1 ICMCB - Institut de Chimie de la Matière Condensée de Bordeaux

While approaching a Mott−Hubbard transition by hole doping of the pristine La2CuO4 cuprate, excitons are created because of exciton−exciton and exciton-doping hole stabilizing interactions. Here, excitons are of charge-transfer Frenkel-type, with effective Cu+O− electrical dipoles that solvate the doping charges. Assuming a moderate screening by charge carriers, we show that mobile exciton-solvated doping holes should be associated in pairs either by a deep energy well or as thermodynamically stable pairs that can glide in the [100] or [010] direction after Bose condensation. Exciton−exciton dipolar interactions constitute thus the “pairing glue” in this model, which is based on instantaneous interactions and intrinsically differs from the previous excitonic models, in which BCS virtual phonons were replaced by virtual excitons.

Mots clés: Charge transfer; Cuprates; High-Tc; Excitons

Domaines: Matériaux

Michel Pouchard, Jean-Pierre Doumerc, Antoine Villesuzanne. Real-space pairing through charge transfer excitons in High-Tc cuprates. Inorganic Chemistry, 2008, 47 (24), pp.11958-11964. ⟨10.1021/ic801266q⟩. ⟨hal-00350956⟩