Raman Spectroscopy of Nanoscale Ferroelectric and Multiferroic Thin Films and Superlattices

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****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.