Very recent findings by our group and others reveal that ferroelectric interfaces can show strongly enhanced properties and remarkable new effects with potential for exploitation in devices. In particular, new phases at broadened domain walls [DWs], conductivity and possibility for ferromagnetism in ferroelectric DWs and giant response in materials possessing high density ferroelectric DWs were shown
DWs form spontaneously in ferroelectrics. Their functionality, widely recognized is neither quantified nor controlled. Distinctly from other interfaces, ferroelectric DWs are mobile, can be modified dynamically by external forces (electrical, stress, temperature variation) and can, moreover, be annihilated and recreated
What are the mechanisms to functionalize DWs? How to gain control over the structure and dynamics of these DWs, and what are the potential breakthroughs that such control may lead to? What additional properties of DWs await discovery? We will address these questions through several interrelated objectives designed to cover both fundamental aspects, as well as limits of applicability
Considering a single DW as a device that can be created, displaced and eliminated reversibly in-situ is unique to this project. Working with ordered arrays of DWs is another central theme. To create controlled patterns of DWs we will use top-down and bottom-up approaches. Characterization of DWs will range from investigation of the internal structure by Spherical Aberration Corrected HRTEM through cryogenic Piezo Force Microscopy study of DW phase-transition, to macroscopic characterization over a broad frequency and driving stimulus range. Theory will guide the investigation. Device concepts will be demonstrated, such as DW-enhanced ultrasonic transducer, DW transistor and ferroelectric string memory
We believe that attainment of these objectives should lead to conceptual breakthroughs both in our understanding of ferroelectric interfaces and in their applications.
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