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TT: Fachverband Tiefe Temperaturen

TT 33: Postersession Correlated Electrons: Metal Insulator Transition, Spin Systems and Itinerant Magnets

TT 33.20: Poster

Mittwoch, 25. März 2009, 14:00–18:00, P1A

Thermodynamic properties of the ferromagnetic Kondo Lattice Model at finite temperatures for different magnetic phases — •Martin Stier and Wolfgang Nolting — Humboldt-Universität zu Berlin, Institut für Physik, Theoretische Festkörperphysik, Newtonstraße 15, 12489 Berlin, Germany

We investigate the ferromagnetic Kondo Lattice Model (KLM) at finite temperatures for different (anti)ferromagnetic phases. To compare the theory with real materials like the manganites we extend the pure KLM by terms describing the Coulomb interaction, the superexchange and a Jahn-Teller splitting. Using a modified RKKY method we determine the various transition temperatures and decide by calculating the free energy which phase is actually present at a given parameter set. Additionally, we can evaluate other important thermodynamic quantities like the entropy or the specific heat.