Ferroelectrics
Prof. Dr. Wolfgang Kleemann (Universität Duisburg-Essen)

This lecture introduces the physics and technological applications of ferroelectric materials, the first of which - "Rochelle-Salz“, NaKC₄H₄O₆·4H₂O - was discovered in 1920 by Valasek. Their spontaneous electric polarization is accompanied by lattice strains and domain patterns, which may be imaged by piezoforce scanning microscopy. The basic features of ferroelectricity are successfully described by Landau's mean field theory of phase transitions despite the different microscopic origins. Disordered ferroelectrics such as Sr_xBa_1-xNb₂O₆ reveal "relaxor" properties due to random internal electric fields. Coexistence of ferroelectric and magnetic orders in "multiferroic" crystals like BiFeO₃ or composites like BaTiO₃/CoFe₂O₄ exhibit magnetoelectric coupling with high potential for applications.
All interested are cordially welcome! Organize your personal meeting with the lecturer by contacting M. Kläui