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Metallic core-shell
nanostructures : synthesis, stability, coupled properties
and novel devices
Funding: NSF/DMR #0501421 (7/05 - 6/09)
Project summary:
The fundamental goal of the proposed 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 builds on the accomplishments of
our recently completed NSF/DMR proposal on "Isolated
and collective magnetic behavior of metallic nanocrystals
and their superlattices" but, at the same time,
explores new direction in materials research 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 are proposed to address their thermodynamic
stability by treating them effectively 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 the microstructure at the nanometer
length scale and correlating it with the observed
properties. It also builds on our earlier observation
of the assembly of nanodisks and proposes a novel
experiment that may well lead to the demonstration
of the smallest magnetoresistive sensor. There is
very broad international scientific participation
in this project as well with collaborative interactions
planned to benefit the training and education of graduate
students. The proposal will have 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 proposal will also
have broad impact on teaching, educational and outreach
activities at UW. Specifically, it will have direct
bearing on both graduate (Magnetic materials, Bonding
and crystallography) and undergraduate (Nanoscience
and nanotechnology) courses that the PI teaches at
UW.
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