Münster 1999 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 15: Postersitzung II: Elektronische Eigenschaften (1-12), Josephson-Kontakte (13-27), Heavy Fermions (28-40), Theorie HTSL (41-48), M-I-Überg
änge, Korrelierte Systeme (49-79)

TT 15.68: Poster

Mittwoch, 24. März 1999, 14:30–18:00, Foy

Paramagnetic metal-insulator transition in the 2D Hubbard model — •Marc Gaston Zacher, Carsten Gröber, and Robert Eder — Institut für Theoretische Physik, Universität Würzburg, Am Hubland, 97074 Würzburg

We study the transition from paramagnetic metal to paramagnetic insulator by finite temperature Quantum Monte-Carlo simulations for the 2D Hubbard model at half-filling. Working at the moderately high temperature T=0.33 t where the spin correlation length has dropped to 1.5 lattice spacings, and scanning the interaction strength U, we observe an unambiguous metal-insulator transition with onset at U_c=4 t. In the metallic phase there are no indications of any ‘correlation narrowing’ of the band width, nor for any decrease of spectral weight at the Fermi energy. The Mott-Hubbard gap opens gradually with increasing U and is accompanied by the formation of side bands near the Fermi energy. In the first stages of gap formation the gap opens at (π,0), reminiscent of the ‘pseudogap’ phenomenology in cuprate superconductors.