Self-Assembled Polvdomain Ferroelectric Heterostructures

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This is a collaborative theoretical and experimental project to study ferroelectric polydomain heterostructures with the objective of achieving greater materials physics understanding and the ability to model and engineer heterostructures with controlled self-assembled polydomain architecture of oxide ferroelectric films for enhanced electrical and mechanical properties. Heterostructures with polytwins (90 deg.-domains) will be considered first. Graphoepitaxial methods will be used to engineer polydomain architectures with controlled domain fractions and periods. Characterization will include information on internal stresses and dislocations. The focus will be to understand how structural characteristics affect the evolution of polarization. A natural extension is the study of ferroelectric heterophase polydomain heterostructures. The rhombohedral-tetragonal phase transformation in relaxor type single crystalline films offers an excellent opportunity to do so. This transformation is accompanied by a significant strain. Therefore, elastic interactions will determine the architecture of the two-phase polydomain state. It is planned to create these architectures and study their electro-mechanical properties as well.%%%The project addresses basic research issues in a topical area of materials science having high potential technological relevance. An important feature of this collaborative, interdisciplinary program is the combined theoretical and experimental approach, and the integration of research and education through the training of students in a fundamentally and technologically significant area. ***