Highlights
Jan 21, 2009
University of Minnesota - Twin Cities
Magnetics Day - Magnetism in Technology
Paul Crowell, Chris Leighton, Dan Dahlberg
MRSEC faculty members Paul Crowell, Chris Leighton, and Dan Dahlberg and their students guided 25 high school students through an exploration of magnetism and its applications to technology as part of the Institute of Technology Center for Education Programs (ITCEP) Exploring Careers in Science & Engineering summer camp. The day of activities included hands-on demos, a lunch with recent graduates working in industry, and an afternoon spent building motors, magnetic levitators, generators, and radios.
Jan 8, 2009
Princeton University
Defect Density Limits Orientational Order in Shear-Aligned Block Copolymer Films
Andy Marencic, Mingshaw Wu, Paul Chaikin (NYU), and Rick Register
Self-assembling block copolymers provide a simple, efficient, and rapid way to generate nanoscale patterns over macroscopic areas:Â’ for example, an array of 20 nm dots covering a 100 mm silicon wafer.Â’ These dots can be "lined up" by applying shear to the block copolymer film [1], but the order is not perfect:Â’ dislocations (lines of dots that abruptly start or end) remain in the film.Â’ In a recent study [2], PCCM researchers have shown that the quality of orientational order of the dots depends only on the density of these dislocations; in the limit that dislocations are
Dec 19, 2008
Northwestern University
Multiscale Patterning of Plasmonic Metamaterials
Joel Henzie, Min Hyung Lee, and Teri W. Odom Northwestern University Materials Research Science & Engineering Center, DMR-0520513
Surface plasmons - collective oscillations of free charges - on metal surfaces have resulted in demonstrations of enhanced optical transmission, collimation of light through a subwavelength aperture, negative permeability and refraction at visible wavelengths, and second-harmonic generation. The structures that display these plasmonic phenomena typically consist of ordered arrays of particles or holes with sizes of the order of 100 nm.
Dec 19, 2008
Northwestern University
Atomic Force Photovoltaic Microscopy
B. J. Leever, M. F. Durstock, M. D. Irwin, A. W. Hains, T. J. Marks, L. S. C. Pingree, and M. C. Hersam Northwestern University Materials Research Science & Engineering Center DMR-0520513
Organic photovoltaic devices (OPVs) hold promise for a variety of applications requiring alternative energy generation. Through a collaboration betweenÂ’ Northwestern University MRSEC IRG 4 and Wright Patterson Air Force Base, a new strategy for characterizing the electrical and optical performance of operating OPVs has recently been developed. Atomic force photovoltaic microscopy allows the photocurrent response in OPVs and other optoelectronically-active materials and devices to be spatially mapped down to the nanometer length scale.
Dec 19, 2008
Northwestern University
The Art of Science and the Science of Art
Katherine T. Faber Northwestern University Materials Research Science & Engineering Center, DMR-0520513
A partnership between the NU-MRSEC and the Art Institute of Chicago provides fertile ground for curriculum development. Lisa Backus, a high school chemistry teacher and participant in the Center's 2006Â’ Research Experience for Teachers (RET) program was inspired by her summer research project working on conservation science problems of Ancient Chinese jades and Winslow Homer watercolors. The result is an art-based high school chemistry module that introduces students to the properties of light, the atom, and organic compound pigments.
Oct 27, 2008
Princeton University
Quantum Memory Preserves Coherence for over 1 Second in Silicon
John J. L. Morton, Alexei M. Tyryshkin, Richard M. Brown, Shyam Shankar, Brendon W. Lovett, Arzhang Ardavan, Thomas Schenkel, Eugene E. Haller, Joel W. Ager and Stephen A. Lyon
One of the key hurdles to building a large quantum computer is maintaining the coherence of the many individual two-level quantum mechanical systems, or qubits. Atoms and ions in a vacuum or nuclear spins in solids and liquids can have long coherence, but it is not yet known how well those systems can be scaled to make a large computer. Ideally one could use the spin of an electron in a semiconductor as a qubit, since modern semiconductor technology is based upon moving and controlling electrons in silicon.
Aug 29, 2008
Princeton University
Phase Transition of Dirac Electrons in Bismuth
Lu Li, Joe Checkelsky, Yew San Hor, Ctirad Uher (Michigan), Arthur Hebard (Florida), Bob Cava, and Phuan Ong
The energy E of a bowling ball increases as the square of its velocity (or momentum p). This is also generally true for electrons in solids, which are accurately described by the Schràƒ’¶dinger equation (Fig. 1a). However, in a small set of materials - e.g. bismuth, antimony and graphene - E increases linearly with p (Fig. 1b). To describe this unusual behavior, we resort to the Dirac equation, which has been very successful in describing neutrinos and high-energy electrons.
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