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MA: Fachverband Magnetismus

MA 24: ThyssenKrupp Dissertations-Preis 2011 der AG Magnetismus

MA 24.3: Vortrag

Dienstag, 15. März 2011, 14:10–14:30, HSZ 04

Order parameters and domain topology in magnetically induced ferroelectrics — •Dennis G. Meier — Helmholtz-Institut für Strahlen- und Kernphysik, Universität Bonn

Watching soccer strikingly demonstrates how important teamwork is for achieving the optimal result. A similar lesson can be learned from nature looking at the symbiosis of whales and cleaner fish or ants and trees, where both sides greatly benefit from team play. In my talk I show that even complex oxides take the advantages that result from close collaborations: Whenever magnetic and electric order “work togethers” and conjointly determine the domain state of the host material, extremely robust and useful topological magnetoelectric correlations arise. These exotic spatial correlations occur in so-called magnetically induced ferroelectrics and are interesting from the scientific point of view, as well as for future spintronics applications, because they can be used to control spin-based properties by electric fields. For a long time related domain structures were inaccessible due to incommensurate antiferromagnetic spin arrangements and a spontaneous polarization being three orders of magnitude smaller than in conventional ferroelectrics. By developing new concepts of second harmonic generation (SHG) topography I found a way to visualize the usually hidden order. Thus, topological correlations and switching dynamics of related materials can now be analyzed on the basis of descriptive SHG images. As an instructive example, the three-dimensional domain topology and switching kinematics of multiferroic MnWO4 are discussed providing an insight into the fascinating domain physics of magnetically induced ferroelectrics.