Dresden 2006 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
TT: Tiefe Temperaturen
TT 25: Correlated Electrons - Poster Session
TT 25.27: Poster
Mittwoch, 29. März 2006, 14:30–18:30, P1
Mesoscopic BCS pairing in the repulsive 1d-Hubbard model — •Andreas Osterloh1, Luigi Amico2, and Andrea Mastellone2 — 1Institut für theoretische Physik, Universität Hannover, Appelstraße 2, D-30167 Hannover, Germany. — 2MATIS-INFM & Dipartimento di Metodologie Fisiche e Chimiche (DMFCI), Universita’ di Catania, viale A. Doria 6, I-95125 Catania, Italy
We study mesoscopic pairing in the one dimensional repulsive Hubbard model and its interplay with the BCS model in the canonical ensemble. The key tool is comparing the Bethe ansatz equations of the two models in the limit of small Coulomb repulsion. For the ordinary Hubbard interaction the BCS Bethe equations with infinite pairing coupling are recovered; a finite pairing is obtained by considering a further density-dependent phase-correlation in the hopping amplitude of the Hubbard model. We find that spin degrees of freedom in the Hubbard ground state are arranged in a state of the BCS type, where the Cooper-pairs form an un-condensed liquid on a “lattice” of single particle energies provided by the Hubbard charge degrees of freedom; the condensation in the BCS ground state corresponds to Hubbard excitations constituted by a sea of spin singlets.