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

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.