Dresden 2011 – scientific programme
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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 19.48: Poster
Tuesday, March 15, 2011, 10:45–13:00, P2
Nonlinear Spectroscopy and Domain Imaging in the High-temperature Multiferroic CuO — Tim Hoffmann1, Kenta Kimura2, •Tsuyoshi Kimura2, and Manfred Fiebig1 — 1University Bonn, HISKP, Germany — 2Osaka University, Japan
Compounds in which the ferroelectric polarization is directly induced by the magnetic structure (joint-order parameter multiferroics) are of special interest because of their intrinsically strong magnetoelectric coupling. In the majority of these systems this effect occurs at temperatures < 50 K. However, in CuO ferroelectricity is induced by a spiral magnetic order at ≈ 230 K. This proves that joint-order-parameter multiferroicity is not limited to the low-temperature regime and renders CuO an important subject of research on the search for large magnetoelectric effects at near-ambient temperatures.
We performed a full characterization of the compound by polarization-dependent optical second harmonic generation spectroscopy. By temperature dependent measurements we could identify the SHG tensor components coupling to the multiferroic state and obtain the temperature dependence of the ferroelectric polarization and the magenetic order parameter, respectively. The gigantic efficiency of the observed SHG signal points to a substantial electronic (instead of ionic) contribution to the ferroelectric polarization. Furthermore we investigated the multiferroic domain structure by spatially resolved SHG and found that in zero-field-cooled samples the domain size is on the order of 0.1-1 µm.