FRG: Quantum Engineering of Metallic and Magnetic Nanostructures

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TECHNICAL: Supported by NSF, which began in 1998, this FRG program developed a novel 'electronic growth' concept, stressing the vital importance of quantum size effects of the itinerant electrons in defining the stability as well as the likely growth mode of metallic thin films on semiconductor substrates. This new concept adds a substantial new facet to the phrase 'quantum engineering', in that quantum effects can now be exploited to precisely control the formation of metallic structures in the quantum regime. Capitalizing on PI's strengths and conceptual advances achieved so far in the broad areas of metallic and magnetic nanostructures, this project aims at pushing the research objectives in three new frontiers: (a) One-dimensional (1D) Electronic Growth and 1D Quantum Structures; (b) Subsurfactant Epitaxy and Quantum Growth of Hybrid Quantum Structures; and (c) Adsorption Energetics, Surface Mobility, and Chemical Reactivity on Quantum Films. In area (a), as 1D electronic systems exhibit sharp spikes in the density of states (DOS), as opposed to the staircase DOS of 2D systems, one expects much stronger quantum size effects. This can potentially be exploited for controlling the formation of 1D quantum structures. The interplay between the spin-resolved DOS and 1D quantum growth will be investigated. In addition, 1D superconductivity will be pushed toward the clean limit and thoroughly explored. In area (b), by integrating the concepts of 'subsurfactant epitaxy' and 'electronic growth', the PIs will fabricate hybrid quantum structures involving superconductors and dilute magnetic semiconductors. Success here will allow to explore the novel concept of charge and spin manipulation in such hybrid systems. In area (c) the PIs will investigate how the quantum stability influences three intimately related surface phenomena: adsorption energetics of atoms and molecules, their surface migration rates, and chemical reactivity on selected catalytic metal films. NON-TECHNICAL: Artificially engineered electronic systems in reduced dimensions occupy a central part in modern materials research. By developing advanced synthesis techniques, materials scientists strive to tailor novel electronic materials through dimensional control with the ultimate atomic precision. The driving force is the realization that, in reduced dimensions, quantum effects are bound to be more pronounced, and may result in intriguing new physical properties of technological significance. The educational goals are manifold. The first is to prepare the next generation of materials scientists in nanoscience and nanotechnology through research training involving postdoctoral researchers, graduate students, and undergraduates. Undergraduate students are recruited through the REU programs in our institutions. The next goal is to provide broader education through the development of a new curriculum and new courses in nanoscience and technology at the graduate and undergraduate levels at both institutions. This educational goal has been achieved successfully and will continue to be pushed to new fronts. Finally, in terms of K-12 nanoscience education, the PIs will recruit high school science teachers through the UTEACH program at Univ. of Texas. In addition, to introduce the concept of nanoscience at the most basic level the PIs also foster a partnership with the Austin Children's Museum to develop demonstration kits for nanoscience education for young children from K-5. Similar efforts have been and will continue to be made at the University of Tennessee. As a specific example, one PI, Zhang, has served as a volunteer science instructor in a local primary school for years and will continue on such efforts.