Regensburg 2004 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 15: Korrelierte Elektronen: Theorie I

TT 15.2: Vortrag

Dienstag, 9. März 2004, 14:45–15:00, H19

Quasi-particle structure and ferromagnetism in the Kondo-lattice model — •Tilmann Hickel and Wolfgang Nolting — Humboldt-Universität, Institut für Physik, Newtonstr. 15, 12489 Berlin

The Kondo-lattice model (KLM) describes an indirect exchange interaction of localized magnetic moments, mediated by itinerant conduction electrons. The quantum-mechanical character of these local spins, which has an substantial impact on the magnetic properties of the concerned materials, prohibits a straight-forward application of standard many-body approaches to the model Hamiltonian. We shall show that the projection-operator method (POM) is instead a valuable analytical technique to obtain substantial statements on one-particle properties of the KLM. It allows the derivation of perturbational results of the same quality as obtained for fermionic models as the Hubbard model. We will use the POM to study the ferromagnetic phase of the KLM and its dependence on material parameters self-consistently. In each step we make sure, that the subsystems of conduction electrons and localized moments are approximated on the same level.