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TT: Tiefe Temperaturen

TT 31: Correlated Electrons: Metal Insulator Transition - Part 2

TT 31.11: Talk

Thursday, March 30, 2006, 16:45–17:00, HSZ 301

Orbital-selective Mott transitions in Hubbard models with orbital-dependent hopping — •Nils Blümer, Carsten Knecht, Krunoslav Požgajčić, and Peter van Dongen — Institut für Physik, Johannes Gutenberg - Universität, 55099 Mainz

The anisotropic degenerate two-orbital Hubbard model is studied within dynamical mean-field theory at low temperatures. High-precision calculations on the basis of a refined quantum Monte Carlo (QMC) method reveal that two distinct orbital-selective Mott transitions occur for a bandwidth ratio of 2 even in the absence of spin-flip contributions to the Hund exchange. The second transition – not seen in earlier studies using QMC, iterative perturbation theory, and exact diagonalization – is clearly exposed in a low-frequency analysis of the self-energy and in local spectra. These published [1] results are complemented with recent studies using QMC and Potthoff’s self-energy functional method.

[1] C. Knecht, N. Blümer, and P.G.J. van Dongen, Phys. Rev. B 72, 081103(R) (2005).