Dresden 2006 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 25: Correlated Electrons - Poster Session

TT 25.28: Poster

Mittwoch, 29. März 2006, 14:30–18:30, P1

Hubbard model in a magnetic field at weak coupling — •Carsten Knecht and P.G.J. van Dongen — University of Mainz, Institut für Physik, 55099 Mainz, Germany

The phase diagram of the half-filled Hubbard model is studied at weak coupling in two spatial dimensions. A homogeneous magnetization in the z-direction and a staggered magnetization in the x-direction are assumed. We apply perturbation theory at fixed order parameter (PTFO) to this system. The results are compared with the well know Hartree-Fock solutions that usually overestimate the order parameters. This calculation is also relevant for superconductivity in the doped two-dimensional negative-U Hubbard model.