Regensburg 2013 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 43: Correlated Electrons: Metal-Insulator Transition 2

TT 43.6: Vortrag

Mittwoch, 13. März 2013, 16:15–16:30, H19

Magnetic susceptibility of the orbital-selective Mott phase — •Markus Greger, Michael Sekania, Marcus Kollar, and Dieter Vollhardt — Theoretische Physik III, Zentrum für Elektronische Korrelationen und Magnetismus, Universität Augsburg

We analyze the low-energy physics of multi-orbital Hubbard models in the orbital-selective Mott phase within Dynamical Mean-Field Theory. Our main focus lies on the calculation of dynamical two-particle quantities, e.g., susceptibilities. They are of particular interest in these systems since the coupling between the orbitals is not due to a hybridization, but is caused by two-particle processes originating from the interaction, i.e., the Hund’s rule coupling J and the inter-orbital repulsion U₁. Employing the Numerical Renormalization Group as an impurity solver we obtain diverging spin-susceptibilities χ_i,j^sp(ω) at ω=0; here i,j are orbital indices. This corresponds to a divergent density of states for magnetic excitations, indicative of an instability of the phase. An explanation based on a Kondo-type Hamiltonian is given. These results also provide a better characterization of the known non-Fermi liquid properties of the phase.