Lattice dynamics and phase transitions in multifunctional oxide nanomaterials studied by ultraviolet Raman spectroscop

非技术性描述：近年来，电子材料的科学和技术已经朝着纳米尺度（十亿分之一米）的人工工程薄膜和多层结构发展。纳米材料表现出与宏观材料截然不同的物理行为，从而为新型器件应用开辟了新的机会。该项目研究纳米铁电体和多铁性材料，这类材料既对基础研究感兴趣，又由于在各种设备中的应用潜力很高而具有实际重要性，例如计算机存储器，微波电子设备或下一代晶体管。该研究与博伊西州立大学的教育计划紧密结合，涉及研究和培训的本科生和研究生，从而使他们为物理科学和材料工程的职业生涯做好准备。这些毕业生是电子和材料行业的需求，如美光科技，惠普，和其他高科技公司在博伊西大都市地区。该项目促进积极使用最先进的仪器用于教育目的，并支持新的研究生课程的发展。它扩大了来自代表性不足群体的学生对尖端科学研究的参与。该项目增强了博伊西州在凝聚态物理和材料科学方面的实力。技术描述：复合金属氧化物是一大类材料，具有各种各样的功能特性，对新型器件应用具有吸引力。在这些功能中有铁电性和铁磁性，材料具有自发的电极化或磁化的性质，它们可以分别通过施加电场或磁场来切换。铁电体和多铁性材料，表现出磁性和铁电性有序的材料，在过去几年中一直是密集研究活动的焦点，由电和磁序参数之间的耦合引起的新型器件应用的潜在新功能驱动。由于新的物理现象和性质显着不同的同质体铁电体，在纳米尺度上的化学工程薄膜和多层结构是特别感兴趣的。本计画利用变温拉曼光谱与紫外线激发来探讨几个对于了解奈米级铁电体与多重铁性的行为具有重要意义的议题，著重于铁电奈米材料的尺寸效应，以及薄膜与异质结构中的温度-应变相图，这些异质结构的新颖材料被预测具有应变薄膜形式的铁电与多重铁性。这些结果用于测试热力学和第一原理理论的预测，并结合结构，电学和磁学性质的彻底表征，从而更全面地了解纳米铁电性和磁电耦合。拟议中的研究将密切结合到博伊西州立大学的教育计划中，积极让本科生和研究生参与研究和培训，并促进持续有效地利用最新的该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查进行评估，被认为值得支持的搜索.

Non-technical description:In recent years, science and technology of electronic materials have moved towards artificially engineered thin films and multilayer structures at nanometer scales (one billionth of a meter). Nanoscale materials exhibit physical behavior drastically different from that of macroscopic materials, thus opening new opportunities for novel device applications. This project studies nanoscale ferroelectrics and multiferroics, a class of materials both interesting for fundamental research and practically important due to high potential for applications in various devices, such as computer memories, microwave electronic devices or in next-generation transistors. The research is closely integrated into the educational program at Boise State University, involving undergraduate and graduate students in research and training, thus making them well prepared for careers in physical sciences and materials engineering. Such graduates are on demand by electronics and materials industries, such as Micron Technology, Hewlett Packard, and other high-tech companies in Boise metropolitan area. The project promotes an active use of the state-of-the-art instrumentation for educational purposes and supports the development of new graduate programs. It broadens the involvement of students from under-represented groups in the cutting-edge scientific research. The project enhances Boise State’s strength in condensed-matter physics and materials science. Technical description:Complex metal oxides are a vast class of materials that have a wide variety of functional properties attractive for novel device applications. Among these functionalities are ferroelectricity and ferromagnetism, properties of materials to possess spontaneous electric polarization or magnetization, which can be switched by applying electric or magnetic field, respectively. Ferroelectrics and multiferroics, materials that exhibit both magnetic and ferroelectric ordering, have been in the focus of intensive research activity in the last several years, driven by potential new functionalities for novel device applications arising from the coupling between the electrical and magnetic order parameters. Artificially engineered thin films and multilayer structures at nanometer scales are of particular interest, due to new physical phenomena and properties dramatically different from those of homogeneous bulk ferroelectrics. This project utilizes variable-temperature Raman spectroscopy with ultraviolet excitation to address several issues of major importance for understanding the behavior of nanoscale ferroelectrics and multiferroics, focusing on size effects in ferroelectric nanomaterials and temperature-strain phase diagrams in thin films and heterostructures of novel materials predicted to have ferroelectric and multiferroic properties in strained thin film form. These results are used to test the predictions of thermodynamic and first-principles theories and combined with thorough characterization of structural, electrical and magnetic properties, leading to a more comprehensive understanding of nanoscale ferroelectricity and magnetoelectric coupling. The proposed research will be closely integrated into the educational program at Boise State University, actively involving undergraduate and graduate students in research and training and promoting the continued effective use of the state-of-the-art optical instrumentation for educational purposes.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.