Metallic Core-Shell Nanostructures: Synthesis, Stability, Coupled Properties and Novel Devices

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The fundamental goal of the research is to investigate the synthesis, stability and coupled functional properties (magnetic/optical and magnetic/spin-dependent transport, magnetic/biofunctionality) of nanometer-size, metallic cores whose surfaces have been modified with metallic shells or chemically functionalized for specific applications. It explores a new direction by synthesizing the next hierarchy of nanoscale building blocks, metallic core-shell structures. Recognizing the importance of surface energies in systems of nanoscale dimensions, experiments address their thermodynamic stability by treating the systems as "nanocrucibles". It addresses the evolution, elucidation and optimization of the coupled properties of surface-engineered nanocrystals, emphasizing size-dependent scaling laws that specifically affect their dynamic magnetic behavior and optical properties. It brings to bear a number of advanced characterization methods that are critical to the evaluation of microstructure at the nanometer length scale and correlating it with the observed properties. It also builds on an earlier observation of the assembly of nanodisks and creates a novel experiment that may lead to the demonstration of the smallest magnetoresistive sensor. There is very broad international scientific participation in this project with collaborative interactions planned to benefit the training and education of graduate students. The research has broad technological impact on a variety of sensing applications that include magnetic recording. Moreover, synthesis and surface functionalization of magnetic core-shell structures could lead to a number of novel therapeutic and diagnostic applications in biomedicine. This includes bio-labeling for contrast enhancement in magnetic resonance imaging, hyperthermia for cancer treatment, magnetic sensors based on dynamic magnetic relaxation, and microfluidic sensors using core-shell structures with coupled magnetic and optical functionalities. The research has broad impact on teaching, education and outreach activities at UW with a direct bearing on both graduate (magnetic materials, bonding and crystallography) and undergraduate (nanoscience and nanotechnology) courses. The latter is taught in a cooperative learning mode with supervised involvement of the graduate students in the education of undergraduates. The PI and his research group, especially the graduate and undergraduate students, are actively involved in outreach activities through the annual UW, College of Engineering open house that is attended by more than 4000 students from local schools. An extensive, interactive and very popular exhibit on magnetism and spinelectronics, developed for the first time last year, will be refined and enlarged in coming years. The PI is committed to enhancing the diversity of graduate student participation in his research program. He is a founding member of the UW Graduate School faculty committee on Recruitment from Minority Serving Institutions. The PI continues to work actively with the Center for Instructional Research and Development (CIDR), the Center for Engineering Learning and Teaching (CELT), the Minority Science and Engineering Program (MSEP), and Women in Science and Engineering (WiSE) to increase the participation of women and people of diverse backgrounds in his teaching and research activities on the UW c