EPITAXY, INTERFACES, AND DOMAIN BOUNDARIES OF ROOM TEMPERATURE MULTIFERROIC MAGNETOELECTRIC FILMS AND HETEROSTRUCTURES

本研究的重点是同时表现出磁性和铁电性的多铁性材料。虽然这是一个研究热点，但目前已知的室温多铁性材料还很少，这些材料的性质还需要更深入的了解，特别是铁电性和磁性之间的耦合，即磁电耦合。最近对铁电和铁磁薄膜在更细尺度上的研究表明，它们的畴壁具有不同于畴壁的独特性质，这些性质可以由外场控制，从而开辟了利用这些局部功能来构建真正的纳米器件的途径。了解畴壁的性质，特别是它们的传输特性和相关的物理特性，对于开发它们巨大的器件潜力至关重要，这可能在长期内导致真正的可重构纳米电子学，其中完全可操作的纳米器件电路可以无限地写入，使用和擦除。 因此，本研究计划将研究在室温下表现出多铁性和磁电性的外延薄膜的迷人特性。特别是它将建立在几个外延室温多铁性薄膜的合成和研究在过去的5年中，表现出一种特殊的畴壁，即在平面取向域之间的边界上的工作的身体。将研究这些特定薄膜的畴壁特性，并非常强调它们所表现出的独特畴壁的局部特性，这在以前从未被研究过。 进一步建立在复杂的多铁性薄膜的外延薄膜生长中获得的专业知识，还将研究具有各种架构的复合磁电薄膜的外延生长，并将使用所生产的室温磁电薄膜制造概念验证设备。 最后，将外延生长中获得的知识扩展到另一类材料，即多铁性或磁电混合有机-无机材料的外延生长，将实现其特性，超越光伏功能，包括铁电，压电，磁性，可能是学生和HQP的热电NT，处于当今该领域研究的前沿。

This research focuses on multiferroic materials exhibiting simultaneously magnetic and ferroelectric properties. Though a field of intense research, there are still very few known multiferroic materials at room temperature, and these materials still need a deeper understanding of their properties, in particular the coupling between the ferroelectric and magnetic properties, namely the magnetoelectric coupling. Recent investigations of ferroelectric and ferromagnetic thin films at a finer scale recently revealed that their domain walls have their own set of unique properties different from those of the domains, which can be controlled by external fields, opening the way to exploit these much localized functionalities to build true nanodevices. Understanding the domain wall properties, in particular their transport characteristics and associated physics, is essential in order to exploit their vast device potential, which could in the long term lead to truly reconfigurable nanoelectronics, where fully operational nanodevice circuits could be written, used and erased indefinitely. This research program will therefore study the fascinating properties of epitaxial thin films that do exhibit multiferroic and magnetoelectric properties at room temperature. In particular it will build on the body of work on the few epitaxial room temperature multiferroic thin films synthesized and investigated during the last 5 years, which exhibit a particular kind of domain walls, namely boundaries between in-plane orientation domains. The domain walls properties of these specific films will be studied, with a very strong emphasis on the local properties of the unique kind of domain walls they exhibit, which have never been studied before. Further building on the expertise acquired in growing epitaxial films of complex multiferroic films, the epitaxial growth of composite magnetoelectric thin films with various architecture will also be investigated and proof-of-concept devices will be fabricated using the room temperature magnetoelectric films produced. Finally, extending the knowledge acquired in epitaxial growth to a further class of materials, the epitaxial growth of multiferroic or magnetoelectric hybrid organic-inorganic materials, will be achieved and their properties, beyond photovoltaic features including ferroelectric, piezoelectric, magnetic, possibly thermoelectric nt for students and HQP in general, at the leading edge of today's research in the field.