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TT: Tiefe Temperaturen

TT 11: Postersitzung II (Metall-Isolator-Überg
änge, Phasenüberg
änge in Quantensystemen, Theorie: Systeme korrelierter Elektronen)

TT 11.17: Poster

Dienstag, 25. März 2003, 14:30–19:00, P2c, P2d

Minimal charge gap in the ionic Hubbard model — •Krunoslav Pozgajcic and Claudius Gros — Universtaet des Saarlandes, Fachbereich Physik, Postfach 151150, G38, D-66041

We study the ionic Hubbard model at temperature T=0 within the mean-field approximation and show that the charge gap does not close completely at the ionic-band insulator to antiferromagnetic insulator transition, contrary to previous expectations. Furthermore, we find a new intermediate phase for on-site repulsions U>U_c for different lattices and calculate the phase diagram for the ionic Hubbard model with alternating U, corresponding to a Cu-O lattice.