Regensburg 2010 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 12: CE: Metal-Insulator Transition 1

TT 12.9: Vortrag

Dienstag, 23. März 2010, 11:45–12:00, H19

Microdomain Formation near the First-Order Metal-Insulator Transition of the Hubbard Model — •Qinyong Liu and Johann Kroha — Physikalisches Institut, Universität Bonn, Germany

Since the metal-insulator transition (MIT) in Mott-Hubbard systems at finite temperature is of first order, there must be a region in the vicinity of the transition where metallic and insulating phases coexist. Thus, in this region insulating microdomains are thermally excited within the thermodynamically stable metallic phase or vice versa. The existence of such microdomains has recently been demonstrated experimentally in VO₂. We calculate the size distribution of microdomains as a function of temperature and Hubbard repulsion U. The electronic spectra and the free energy per site are calculated in metallic and in insulating regions as well as across a metal-insulator domain wall, using the generalization of dynamical mean field theory (DMFT) for inhomogeneous systems, with the non-crossing approximation (NCA) as impurity solver. The domain-size distribution is obtained from the resulting free energy difference, including volume and domain wall energies, and exhibits non-trivial, non-monotonic behavior. The first-order MIT of Mott-Hubbard systems may, hence, be viewed as a percolation problem with an anomalous resistivity due to self-generated domain disorder.