Dresden 2009 – scientific programme
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MA: Fachverband Magnetismus
MA 38: Multiferroics
MA 38.13: Talk
Thursday, March 26, 2009, 18:30–18:45, HSZ 103
Many-particle Approach to Multiferroic Bulk Systems — •Thomas Michael1, Steffen Trimper1, and Julia M. Wesselinowa2 — 1Institute of Physics, Martin-Luther-Universitaet, Halle (Saale), Germany — 2Department of Physics, University of Sofia, Sofia, Bulgaria
Multiferroic bulk systems are studied in a many-particle approach. The magnetization, polarization, excitation energies, associated dampings of ferroelectric and magnetic modes are presented as a function of temperature. An anomaly in the ferroelectric quantities close to the magnetic phase transition is observed. The analysis of the ferroelectric subsystem is based on a two-state quantum model, the Ising model in a transverse field. The magnetic moments interact via the Heisenberg model. The corresponding multiferroic coupling term differs for hexagonal and orthorhombic materials. A Green's function technique in reciprocal space provides the static and dynamic properties. Furthermore, we present the dielectric function of the coupled model. The theoretical result are compared with experimental data.