Highlights
Apr 26, 2011
Johns Hopkins University
EXAFS Studies of Local Structure in MTJ
A. K. Rumaiz, J. C. Woicik, W. G. Wang, J. Jordan-Sweet, G. H. Jaffari, C. Ni, J. Q. Xiao, and C. L. Chien,
Background: CoFeB-MgO magnetic tunnel junctions (MTJs) are leading spintronic devices that relies on quantum Mechanical tunneling of electrons from one magnetic metal (CoFeB) to another across an insulating barrier of MgO. The electrical resistance of such MTJs is dictated by the orientation of the two CoFeB metals, parallel or antiparallel. The performance of MTJ is measured by tunneling magnetoresistance (TMR), which is only 20% initially, but greatly increases to 200% after high temperature annealing (Fig. 1). We reveal the evolution of the local structure during annealing.
Apr 25, 2011
Johns Hopkins University
High School Student Research Internships at the Johns Hopkins
Background: The JHU MRSEC conducts extensive K-12 educational
outreach programs aimed at promoting interest in and awareness of the
importance of modern materials research. High school students from the
greater Baltimore area receive four-week internships each July to
conduct research in the laboratories of the JHU MRSEC. The students are
mentored by Center faculty, and also work closely with graduate students
and/or postdoctoral fellows. At the end of the month, each student
gives a 20-minute talk describing his/her project at a symposium
Apr 25, 2011
Johns Hopkins University
Dynamics of Magnetic Charges in Spin Ice
P. Mellado, O. Petrova, Y. C. Shen, and O. Tchernyshyov,
Background: A bar magnet has two poles, denoted as +1 and -1 magnetic charges. Patterned structuresconsist of many magnets (Fig. 1), where the square array (Fig. 1a) does not, whereas the honeycomb (Fig. 1b) has, net magnetic charges (or magnetic monopoles). Under a magnetic field these local magnetic monopoles will move (Fig. 1c). This latter structure is called “spin ice”, because it has a large number of nearly degenerate configurations. This work: We propose a theoretical model of the dynamics in artificial spin ice under an applied
Apr 11, 2011
University of California, Santa Barbara
Multi-domain ordering of coacervate-core based hydrogels unraveled by SANS and solid-state DNP
Craig Hawker and Ed Kramer
A novel category of hydrogel material has been developed (Hawker, Kramer)that form spontaneously in water through complexation of polyelectrolyte endblocks of PEG-based triblock polyelectrolytes—inspired by Waite’s mussel adhesion studies.
SANS (Kramer) and dynamic nuclear polarization (DNP)-enhanced NMR; (Han) reveal that these complexes form dense, yet fluid, coacervate core domains with significant ordering.
Apr 11, 2011
Massachusetts Institute of Technology
Self-beating plastic gels can be induced to change size and color on demand
Chen, I.C., Kuksenok, O., Yashin, V.V., Moslin, R.M., Balazs, A.C., & Van Vliet, K.J. (MIT MRSEC, IRG-III)
Special types of plastic gels that can be induced chemically to undergo self-oscillating changes in shape and color have been known for many years. Van Vliet and Balazs have now found that the oscillations of these self-beating gels can be controlled by their shape and size, as well as by externally applied forces. With change in chemistry, the gels can oscillate on their own from red to blue or green to yellow, for many hours. When these gels are made small enough (
Apr 11, 2011
Massachusetts Institute of Technology
Nanostructured carbon electrodes improve performance of batteries and capacitors
S. W. Lee, B. M. Gallant, H. R. Byon, P. T. Hammond, and Y. Shao-Horn (MIT MRSEC, IRG-I)
The continued evolution of portable electronic devices and micro-electro-mechanical systems (MEMS) requires multi-functional microscale energy sources that have high power, high energy, long cycle life, and the adaptability to various substrates.
Apr 2, 2011
Harvard University
NEW.MECH New England workshop on the Mechanics of Materials and Structure
D.A. Weitz and C.M. Friend
The New England Workshop on the Mechanics of
Materials and Structures, NEW.Mech, was held at Harvard University, Cambridge,
MA on September 25th, 2010. NEW.Mech
was a one-day workshop that brought together the New England Mechanics
community with an interest in exploring new directions on the Mechanics of Soft
Materials and Structures and in sharing the latest advances in the field. The workshop was modeled after the
MRSEC-sponsored New England Complex Fluids Workshop. It was very successful, with more than 200 participants,
Mar 28, 2011
Harvard University
Softer-than-Skin Electronics, Sensors, and Adaptive Materials
R.J. Wood, G.M. Whitesides, and Z. Suo
Soft robotics, wearable computing, and mechanically adaptive structures will lead to revolutionary tools for exploration, disaster relief, personal electronics, and assistive medicine. Progress demands innovative solutions to current challenges: electronic skin for tactile sensing, and soft, hyperelastic circuits for stretchable computing. These new materials will enable next-generation machines and electronics to be soft, durable, impact resistant, and capable of adapting their shape, mechanical properties, and functionality to rapid changes in user environmental conditions.
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