Dresden 2011 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 19: Poster I (Bio- and Molecular Magnetism/ Magnetic Particles and Clusters/ Micro- and Nanostructured Magnetic Materials/ Magnetic Materials/ Multiferroics/ Magnetic Shape Memory Alloys/ Electron Theory of Magntism/ Spincaloric Transport/ Magnetic Coupling and Exchange Bias/ Magnetization Dynamics/ Micromagnetism and Computational Magnetics)

MA 19.47: Poster

Dienstag, 15. März 2011, 10:45–13:00, P2

Response of hexagonal multiferroic RMnO3 (R=Y, Yb, Ho, Er) to magnetic and electric fields — •Sebastian Manz, Tim Günter, Thomas Lottermoser, and Manfred Fiebig — HISKP, University of Bonn, Germany

Contradictory reports on the electric and magnetic properties of the multiferroic hexagonal RMnO₃ compounds and their behavior in electric and magnetic fields are found in literature. Examples are the magnetic structure itself, critical field values for the magnetic phase transition, or the electric coercive field and saturation polarization values. These uncertainties further lead to controversial discussions of the magnetoelectric effects to be expected in the RMnO₃ system.

Here, we report on a systematical analysis of the response of hexagonal multiferroic RMnO₃ to magnetic and electric fields by linear and nonlinear optical techniques and pyroelectric current measurements. The response of samples grown from the flux at different dates and floating-zone samples are compared. We find that the magnetic hysteresis curve can display ferromagnetic, induced ferromagnetic, and ferrimagnetic behavior. Furthermore, we demonstrate that flux-grown samples can no longer be fully polarized at temperatures < 260 K and, due to sample leakage, not at all in the majority of floating-zone samples. We discuss the consequences for electric-field poling experiments reported in the literature.