Highlights

Members of IRG-III of the MIT MRSEC have demonstrated a light emitting device application of such quantum dots. They show that white light can be generated in a layered device that combines organic semiconductor layers with a single monolayer of quantum dots. The composition and the sizes of the quantum dots were chosen to cover the color spectrum required for the perception of white light, as in an incandescent light bulb. The ability to synthesize nanomaterials with nearly atomic precision

Jan 16, 2007

Massachusetts Institute of Technology

Nanocoatings Harvest Water from Fog

In the Namib Desert in Namibia, Africa, a tiny beetle is able to convert microscopic droplets of water present in a morning fog into larger sized droplets that are directed into the beetle's mouth to quench a

Figure 1. Schematic of the spin arrangement in an Fe / Cr thin film bilayer. The wavelength of the spin density wave in the Cr changes continuously as the temperature is varied. This leads to an oscillation in the magnitude of the Cr interface spin with temperature, and therefore an oscillating exchange bias.

Jan 10, 2007

University of Minnesota - Twin Cities

Probing Spin Density Waves

Magnetism in metallic films and interfaces has been intensively studied since the discovery of Giant MagnetoResistance (GMR) in the late 1980s. This effect enabled fabrication of high sensitivity magnetic field sensors for the read heads in magnetic hard disks, revolutionizing magnetic recording. GMR occurs in structures where an ultra-thin "non-magnetic" film is sandwiched between two magnets, Fe / Cr / Fe being a popular example. Although often ignored, the weak magnetism of the Cr film is fascinating in its own right.

Dec 20, 2006

Stanford University

Patterning of Large Arrays of Organic Semiconductor Single Crystals

Alejandro L. Briseno1,2, Stefan C.B. Mannsfeld1, Mang M. Ling1, Shuhong Liu1, Ricky J. Tseng2, Colin Reese1, Mark E. Roberts1, Yang Yang2, Fred Wudl2, Zhenan Bao1 1. Department of Chemical Engineering, Stanford University, Stanford, California 94305, USA 2. Department of Chemistry and Biochemistry and Exotic Materials Institute, Department of Materials Science and Engineering, University of California-Los Angeles, Los Angeles, California 90095, USA

Field-effect transistors made of single organic crystals are ideal for studying the charge transport characteristics of organic semiconductor materials. Their outstanding device performance, relative to that of transistors made of organic thin films, makes them also attractive candidates for electronic applications such as active matrix displays and sensor arrays. The only approach currently available for creating single crystal devices is manual selection and placing of individual crystalsâ€”a process prohibitive for producing devices at high density and with reasonable throughput.

Dec 15, 2006

University of Wisconsin - Madison

A New Organic-Inorganic Heterojunction: GaN-Pentacene

Organic semiconductor materials have shown promise in recent years for use in low-cost electronics applications such as photovoltaics, chemical sensors, and flat-panel displays. In particular, pentacene thin films have been shown to exhibit high a large field-effect mobility on the order of 1 cm2/Vs, which is sufficient for organic thin-film transistors (TFTs) for displays.

Dec 7, 2006

University of Nebraska - Lincoln

Light Used as a Magnetic Hammer

Roger Kirby Group (Nebraska MRSEC)

Scientists in the University of Nebraska MRSEC are using very short light pulses from a femtosecond laser to perturb magnetic materials and to probe their behavior at times after the perturbation. The light pulses are only about 100 millionth-billionths of a second long.

Dec 7, 2006

University of Maryland - College Park

Capturing Atomic Spirals

M. Ranganathan, D.B. Dougherty, W.G. Cullen, T. Zhao, J.D. Weeks and E.D. Williams

Dec 6, 2006

California Institute of Technology

Active Nanophotonic Materials and Devices

The recent decade has seen an explosion of optical communication. Yet much of the information processing is conducted electronically since there have been few truly tunable optical devices. Ferroelectric materials offer a potential solution. They possess interesting nonlinear properties that can be used to design and fabricate unique active tunable nanophotonic devices. Photonic crystals are synthetic hetero-structures that provide an unprecedented ability to manipulate light including slowing down and reflecting selected frequencies.

Dec 5, 2006

University of Nebraska - Lincoln

Controlling Magnetism through a Ferroelectric Switch

Chun-gang Duan, S. S. Jaswal, E. Y. Tsymbal (Nebraska MRSEC)

Dec 4, 2006

Microtubules in Capped Channels: The Persistence of Circulation

In eukaryotic cells, kinesin motor proteins transport intracellular cargo along microtubules, 25 nm protein filaments that form the cell cytoskeleton. This biomotor transport system is of fundamental importance in cell function and dysfunction, and provides a model system for nano- and microscale transport in engineered systems.