Regensburg 2007 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 5: Correlated Electrons - (General) Theory
TT 5.5: Vortrag
Montag, 26. März 2007, 15:15–15:30, H18
Nature and order of orbital-selective Mott transitions — •Nils Blümer1 and Krunoslav Požgajčić2 — 1Institut für Physik,
Johannes Gutenberg-Universität, 55099 Mainz — 2Institut für Theoretische Physik, J.W. Goethe-Universität, 60438 Frankfurt
Motivated by experiments on Ca2−xSrxRuO4, numerous theoretical studies have recently explored the possible occurence of orbital-selective Mott transitions (OSMTs) in multi-band Hubbard models with orbital-dependent hopping amplitudes. By now, consensus has been reached that (within dynamical mean-field theory, DMFT) a sequence of two orbital-selective transitions occurs generically in the two-band case – even in the case of Ising-type Hund rule couplings. However, the precise nature and thermodynamic order of each of these transitions (which may be different for T>0 and T=0) have remained controversial.
In order to address these issues, we directly compute first derivatives of the free energy within DMFT using quantum Monte Carlo (QMC) simulations at T>0 and selfenergy functional theory (SFT) at T=0. High precision is achieved in QMC by using analytic high-frequency corrections and in SFT by including multiple bath sites per orbital, respectively, and checked by comparisons of SFT data with T→ 0 extrapolated QMC results.