Raman Spectroscopy of Nanoscale Ferroelectric and Multiferroic Thin Films and Superlattices

* 非技术性摘要 * 电子材料的现代科学和技术越来越关注纳米（十亿分之一米）尺度上的新型人工工程结构的开发。 材料在纳米尺度下的物理行为在许多方面与宏观材料的物理行为主要不同，这为设计具有用于器件应用的上级性质的材料开辟了新的机会。 该项目将通过实验研究纳米铁电体和多铁性的基本物理特性，这是一种有趣且实际重要的电子材料，具有在各种设备中应用的高潜力，例如计算机存储器或微波电子设备。 该项目将利用光学光谱技术来探测各种条件下与原子振动和结构转变有关的基本性质。 该项目的实验结果将检验当前铁电体和多铁性理论的有效性，从而有助于全面了解它们的性质。 拟议的研究将紧密结合到教育计划在博伊西州立大学，涉及本科生和研究生的研究和培训，促进国家的最先进的光学仪器的积极使用的教育目的，并支持新的研究生课程的发展。* 技术摘要 * 铁电体是具有自发极化的材料，其可以通过施加电场来切换。 铁电体和多铁性材料，表现出磁性和铁电性有序的材料，是许多活跃的研究的焦点，有大量的基础科学需要研究和新的应用需要探索。 近年来，铁电材料和多铁性材料的科学和技术已经向纳米尺度的人工工程薄膜和多层结构发展。 晶格振动的动力学是铁电体的基本性质，与它们的许多重要物理性质相关，并且拉曼光谱是用于研究晶格振动的最强大的分析技术之一。 本计画将利用紫外拉曼光谱来探讨几个对于了解奈米铁电体与多铁性的行为具有重要意义的问题，例如薄膜与异质结构的温度-应变相图、电场对晶格动力学与相变的影响、非化学计量对同质与异质磊晶铁电薄膜性质的影响、以及新型材料的应变膜中的铁电和结构转变。 拟议的研究将紧密结合到博伊西州立大学的教育计划，积极参与本科生和研究生的研究和培训，并促进国家的最先进的光学仪器的持续有效使用的教育目的。

****NON-TECHNICAL ABSTRACT****Modern science and technology of electronic materials increasingly focuses on the development of novel, artificially engineered structures on the nanometer (one billionth of a meter) scale. The physical behavior of materials at the nanoscale is principally different from that of macroscopic materials in many aspects, opening new opportunities for the design of materials with superior properties for device applications. This project will experimentally investigate the fundamental physical properties of nanoscale ferroelectrics and multiferroics, an interesting and practically important class of electronic materials with high potential for applications in various devices, such as computer memories or microwave electronic devices. The project will utilize optical spectroscopic techniques to probe fundamental properties related to the atomic vibrations and structural transformations under a variety of conditions. The experimental results of the project will test the validity of current theories of ferroelectrics and multiferroics, thereby contributing to a comprehensive understanding of their properties. The proposed research will be closely integrated into the educational program at Boise State University, involving undergraduate and graduate students in research and training, promoting an active use of the state-of-the-art optical instrumentation for educational purposes, and supporting the development of new graduate programs. ****TECHNICAL ABSTRACT****Ferroelectrics are materials possessing a spontaneous electric polarization, which can be switched by the application of an electric field. Ferroelectrics and multiferroics, materials that exhibit both magnetic and ferroelectric ordering, are the focus of much active research with an abundance of basic science to be studied and novel applications to be explored. In recent years, science and technology of ferroelectrics and multiferroics have moved towards artificially engineered thin films and multilayer structures at nanometer scales. The dynamics of lattice vibrations is a fundamental property of ferroelectrics, related to many of their important physical properties, and Raman spectroscopy is one of the most powerful analytical techniques for studying the lattice vibrations. This project will utilize ultraviolet Raman spectroscopy to address several issues of major importance for understanding the behavior of nanoscale ferroelectrics and multiferroics, such as temperature-strain phase diagrams of thin films and heterostructures, the effect of an electric field on lattice dynamics and phase transitions, effects of off-stoichiometry on the properties of homo- and heteroepitaxial ferroelectric films, and ferroelectric and structural transformations in strained films of novel materials. 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.