Berlin 2008 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 32: Correlated Electrons: Poster Session

TT 32.68: Poster

Donnerstag, 28. Februar 2008, 14:00–18:00, Poster B

Calculation of Magnetic Phases and Resistivity in an Extended Two-band Kondo Lattice Model — •Martin Stier and Wolfgang Nolting — Festkörpertheorie, Institut für Physik, Humboldt-Universität,12489 Berlin, Germany

We use an extended two-band Kondo lattice model (KLM) to investigate the occurrence of different (anti-)ferromagnetic phases depending on several model parameters. With regard to real CMR-materials like the manganites we have added a Jahn-Teller term, direct antiferromagnetic coupling and Coulomb interaction to the basic KLM. The use of an interpolating self-energy approach and a modified RKKY treatment allows us to calculate the model's electronic and magnetic properties self-consistently. Thereby we are not restricted to classical spins. We present zero-temperature phase diagrams which show a strong influence on the important parameters (Hund's coupling, direct antiferromagnetic exchange, Jahn-Teller distortion, different Coulomb interactions). Some of those calculations can be extended to finite temperatures. Our theoretical results are in good agreement with experimental measurements.