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DF: Fachverband Dielektrische Festkörper

DF 4: Multiferroics I (Joint Session of MA, DF, KR, DS)

DF 4.5: Vortrag

Montag, 22. März 2010, 11:30–11:45, H3

Multiferroic materials with a non-collinear spin structure - A many-particle approach — •Thomas Michael¹, Julia M. Wesselinowa², and Steffen Trimper¹ — ¹Institute of Physics, Martin-Luther-Universität Halle-Wittenberg, Germany — ²Department of Physics, University of Sofia, Sofia, Bulgaria

Multiferroic bulk materials with a conical spin structure are investigated in the framework of a many-particle approach. The analysis of the ferroelectric subsystem is based on a two-state quantum model. Magnetic moments interact via the Heisenberg model. The canting of the spins is incorporated by the Dzyaloshinski-Moriya interaction. A representation of the spin operators with an arbitrary quantization axis is chosen. Minimizing the free energy yields the direction of the quantization axis. The multiferroic coupling term is discussed. A Green’s function technique in reciprocal space provides the temperature dependence of the magnetization, polarization and the energy of the excitations.