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TT: Tiefe Temperaturen

TT 25: Correlated Electrons - Poster Session

TT 25.50: Poster

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

Doping an antiferromagnetic Mott insulator in two dimensions: A variational cluster approach — •Matthias Balzer, Michael Potthoff, and Werner Hanke — Institut für Theoretische Physik und Astrophysik, Universität Würzburg, Germany

The two-dimensional single-band Hubbard model at zero temperature is studied within the variational cluster approach (VCA) [1] using clusters with up to 8 sites. A ficticious staggered magnetic field and an overall shift of the single-particle energies in the reference clusters are used as variational parameters to ensure a thermodynamically consistent determination of the staggered magnetization and the average particle number [2]. Static quantities as well as the one-particle spectral density are calculated as functions of the chemical potential. The system undergoes a transition from the antiferromagnetic Mott insulator at half-filling to a paramagnetic metal at small doping. The critical dopings on the hole- and on the electron-doped side as well as the order of the phase transition are determined. An additional next-nearest-neighbor hopping is taken into account to study a possible phase separation into macroscopically large antiferromagnetic metallic and paramagnetic metallic regions.

[1] M. Potthoff, M. Aichhorn, and C. Dahnken, PRL 91, 206402 (2003)

[2] M. Aichhorn, E. Arrigoni, M. Potthoff, and W. Hanke, preprint