Dresden 2009 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

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

TT 33.22: Poster

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

Spin waves in the Heisenberg and in the Kondo-lattice Model — •Andrej Schwabe and Wolfgang Nolting — Institut für Physik, Humboldt-Universität, Newtonstraße 15, 12489 Berlin, Germany

We present a new approach to the 3D ferromagnetic Heisenberg model being bosonized by the Dyson-Maleev transformation. Magnon excitation energies and line widths are derived by applying the method of moments with a broadened magnon spectral density.
Furthermore, we extend the investigation to the ferromagnetic Kondo-lattice model that can be mapped onto an effective Heisenberg model by using the modified RKKY interaction and the Interpolating Selfenergy Approach. Magnon energies and line widths are calculated for the limiting cases relevant to manganites and ferromagnetic semiconductors. The dependence on band occupation n, intra-atomic exchange J and temperature is investigated. Both zone boundary magnon softening and anomalous magnon damping are found.