Dresden 2003 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 22: Metall-Isolator-Überg
änge in Quantensystemen II
TT 22.1: Vortrag
Freitag, 28. März 2003, 10:15–10:30, HSZ301
Antiferromagnetism and the Metal-Insulator Transition in the Frustrated Hubbard Model — •Robert Zitzler, Thomas Pruschke, and Ralf Bulla — Theoretische Physik III, Institut für Physik, Universität Augsburg, D-86135 Augsburg, Germany
We investigate the magnetic phase diagram of the frustrated Hubbard model in the Dynamical Mean Field theory. The effective impurity problem is solved using Wilson’s Numerical Renormalization Group theory, adapted for phases with broken symmetry. At T=0, we find a discontinuous transition from a paramagnetic metal to an antiferromagnetic insulator at some critical value of the interaction Uc2. In addition, we find hysteresis, where approaching the transition from the insulating phase the system becomes metallic at Uc1 < Uc2, indicating a first order transition. At finite temperatures, this behaviour persists up to some critical temperature, above which there is a second order transition from a paramagnetic to an antiferromagnetic phase. Furthermore we adress the question of how the first order Mott transition evolves in the antiferromagnetic state once TN is suppressed below the critical point of the MIT in the paramagnet.