By exploration of smaller and still smaller length scales, much has been learned
about the fundamental interactions in nature. At the other extreme, condensed matter
physicists have studied the collective statistical behavior of large numbers of
particles. In a merging of these two approaches, intermediate size systems with
relatively small numbers of atoms have recently been fabricated and studied. Novel
effects have been discovered in these so-called mesoscopic systems. Traditionally these
are samples of extremely small volume. But model systems with enlarged “atoms”, such as
vortices in superconducting networks, may suffice. Recent advances in the understanding
of disordered systems, critical phenomena, and non-linear dynamics have also made it
irresistible to ask deeper questions about complexity. Professor Israeloff’s approach is
to probe model complex materials with novel mesoscopic techniques, with an emphasis on
noise measurements and analyses. 

Experiments in progress or under development include mesoscopic studies of
superconducting, disordered, and biological materials. The detailed dynamics of vortices
in superconductors and superconducting networks are of interest. The vortices are
localized regions of magnetic field penetration, around which circulate super-currents.
These vortices must be pinned or nailed down, else they dissipate energy destroying the
superconductivity. Also of interest are exotic transitions between the various fluid,
crystalline, and glassy vortex phases which have recently been discovered. Understanding
strongly driven motion of vortices may shed light on other complex problems, such as
friction, granular flow, invasion, and charge transport. Strongly-driven vortex motion
and localization effects are currently being studied in artificially disordered
superconducting networks. 

A full understanding of the transition between a liquid and a disordered solid such as
ordinary window glass remains as a major unsolved problem in physics. The slow relaxation
of a glass toward equilibrium, though also poorly understood, serves as a prototype for
phenomena found in a wide variety of complex systems such as neural networks, protein
folding, magnetic materials, and superconductors. Recent ideas suggest the answers to
these mysteries lie in the mesoscopic regime. Using novel atomc force microscopy (AFM)
techniques, developed in his laboratory, mesoscopic scale (nanometer) fluctuations in
dielectric and viscoelastic properties have been observed and are being investigated near
the glass transition. The techniques are also being developed into non-invasive
nano-scale probes of advanced integrated circuits and materials.

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Direct observation of molecular cooperativity near the glass transition (with E. Vidal Russell), Physics Faculty Publications (2000)

We describe direct observations of molecular cooperativity near the glass transition in poly-vinyl-acetate (PVAc), through...

 

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High-sensitivity ferromagnetic resonance measurements on micrometer-sized samples (with S. Zhang, S. A. Oliver, and C. Vittoria), Electrical and Computer Engineering Faculty Publications (1997)

Ferromagnetic resonance measurements were taken on a 4 μm diam disk using a planar microwave...

 

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Ferromagnetic resonance of micrometer-sized samples (with S. Zhang, S. A. Oliver, A. Widom, and C. Vittoria), Electrical and Computer Engineering Faculty Publications (1997)

Submicrometer-sized slotline and coplanar waveguide devices were used for ferromagnetic resonance (FMR) measurement on submicrometer-sized...