Dresden 2009 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 40: Poster II: Bio- and Molecular Magnetism (1-9); Magnetic Coupling Phenomena/Exchange Bias (10-15); Magnetic Particlicles and Clusters (16-29); Micro and Nanostructured Magnetic Materials (30-51); Multiferroics (52-64); Spin Injection in Heterostructures (65-67); Spin-Dyn./Spin-Torque (68-93); Spindependent Transport (94-108)

MA 40.55: Poster

Freitag, 27. März 2009, 11:00–14:00, P1A

Topology of the electric order in multiferroic orthorhombic DyMnO₃ by SHG spectroscopy — •Tim Günter¹, Dennis Meier¹, Thomas Lottermoser¹, Dimitri Argyriou², and Manfred Fiebig¹ — ¹HISKP, University of Bonn, Germany — ²Helmholtz Centre Berlin for Materials and Energy, Germany

Multiferroics where a spontaneous electric polarization forms as a direct consequence of magnetic spiral order are of great interest. However, essential aspects of their ferroicity and the precise nature of the large magnetoelectric effects displayed by these compounds remain unclear. One set of these so-called spin-spiral multiferroics are the perovskite manganites RMnO₃ (R=Tb, Dy). Here we report on the investigation of orthorhombic DyMnO₃ by second harmonic generation (SHG) spectroscopy and topology. Due to its high absorption in the visible range a detectable SHG signal requires using femtosecond laser pulses in a reflection geometry. Performing SHG polarization analysis based on SHG selection rules allows the separation of crystallographic background and magnetically induced ferroelectric contributions. A clear evidence of the observation of the magnetically induced electric order below ≈ 19 K was given by the temperature dependence and the spectral distribution of the SHG contributions. In addition, first results on the imaging of magnetically induced ferroelectric domains are reported. A detailed investigation of DyMnO₃ allows to generalize results gained on other spin-spiral multiferroics displaying magnetically induced ferroelectricity like MnWO₄ and TbMn₂O₅.