Highlights
Jun 4, 2009
Princeton University
Discovery of a Topological Insulator Bi2Se3 with a Single Surface Dirac Cone
In an ordinary insulator, such as diamond, the occupied electronic states are separated from unoccupied states by a large energy “gap”. The gap prevents current flow when an electric field is applied. Recent research has uncovered a new class of insulators, called topological insulators, in which electrons can bypass the energy gap by moving in surface states. The energy vs. momentum dispersion of these unusual surface states are Dirac-like. They exhibit unusual topological properties which may be important for quantum computing.
Jun 3, 2009
Massachusetts Institute of Technology
High-energy batteries using genetically-engineered viruses
Angela Belcher, Gerbrand Ceder, Woo-Jae Kim, Yun Jung Lee, Michael S. Strano, Hyunjung Yi, and Dong Soo Yun (MIT); Kisuk Kang (Korea Advanced Institute of Science and Technology)
Professor Belcher previously engineered viruses that could build an anode by coating themselves with cobalt oxide and gold and self-assembling to form a nanowire.
In the new work, the research team created a cathode to pair with the anode: they genetically engineered viruses that first coat themselves with iron phosphate, then attach to carbon nanotubes to create a highly conductive material.
Jun 2, 2009
University of Maryland - College Park
Origin of the Colossal Electromagnon in Multiferroic RMnO3
R. Valdés Aguilar1, M. Mostovoy2, A. B. Sushkov1, C. L. Zhang3, Y. J. Choi3, S-W. Cheong3, and H. D. Drew1 1Department of Physics, University of Maryland, College Park, Maryland 20742, USA 2Zernike Institute for Advanced Materials, University of Groningen, 9747 AG Groningen, The Netherlands 3Rutgers Center for Emergent Materials and Department of Physics & Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA
In multiferroic materials, where magnetism and ferroelectricity coexist, it is possible to excite mixed spin and lattice vibrations with electromagnetic waves called electromagnons. We find that the mechanism responsible for electromagnons is different from the one that couples static magnetism and ferroelectricity. Our results show how the strong coupling of spin and lattice excitations produce the colossal electromagnon observed in RMnO3. This mechanism can also exist in non-multiferroic materials.
May 24, 2009
Yale University
CRISP High resolution non-contact Atomic Force Microscope (AFM)
B. J. Albers, T. C. Schwendemann, M. Z. Baykara, N. Pilet, E. I. Altman, and U. D. Schwarz, Yale University
Understanding the locations of atoms as they are deposited on a surface is critical for growing interfaces of electronicÂ’ device quality. One unique tool that is key to this endeavor, is the high-resolution, low-temperature ultrahigh vacuum scanning probe microscope for simultaneous operation in noncontact atomic force microscopy and scanning tunneling microscopy mode at 4 K available at CRISP (Yale).
Download High resolution non-contact AFM Highlight
May 24, 2009
Yale University
Seeing is Believing
Christine Broadbridge, Southern Ct. State Univ. Heather Edgecumbe, Southern Ct. State Univ.
Made possible by a grant from the Connecticut Office of Workforce Competitiveness (OWC) the goal is to provide Connecticut's teachers with cutting edge imaging tools for their classrooms. A table top scanning electron microscope (mini-SEM) with elemental analysis capabilities was purchased. Typical SEMs are large and require extensive training and maintenance. Initially teachers at high schools and Connecticut's Community Technical Colleges (CTCs) are targeted for professional development and implementation.
May 21, 2009
Massachusetts Institute of Technology
Magnetically-responsive stiffness of carbon nanotube arrays
Markus Buehler (MIT)
Professor Buehler of IRG-II has employed atomistic-based multiscale simulations to theoretically demonstrate the concept of “mechanomutability," i.e. the capability of a material to change its mechanical properties reversibly in response to an external stimulus.
May 19, 2009
Harvard University
Cooking and Science: A Conversation on Creativity
Ferran Adriàƒ’ (El Bulli, Barcelona, Spain)
With over 2 million requests annually for only 8,000 reservations at El Bulli, the renowned restaurant is harder to get into than Harvard. During his visit to the MRSEC in December 2008, El Bulli founder and globally celebrated chef, Ferran Adriàƒ’ , talked with students in the Innovations course, discussed ways of bringing Center research on soft matter to the development of new foods, and gave an enthusiastically received public lecture on the dynamic relationship between modern science and modern cuisine. His visit was covered by Time and the local news stations.
May 19, 2009
Harvard University
New Ordered Hierarchical Helical Assemblies
Boaz Pokroy, Sung H. Kang, L. Mahadevan, and Joanna Aizenberg
Mesoscale hierarchical helical structures with diverse functions are abundant in nature.
May 17, 2009
Brandeis University
Self-Limited Self-Assembly of Chiral Subunits
Yasheng Yang, Robert Meyer, Michael Hagan
A simple computational model demonstrates the assembly of self-limited filamentous bundles. The images are taken from dynamic Monte Carlo simulations in which chiral subunits spontaneously assemble under different interaction strengths and degrees of chirality. (a) Moderate interactions and moderate chirality reproducibly lead to a self-limited bundle with three layers of subunits, while stronger chirality (b) results in a self-limited two-layer bundle. (c) With strong interactions, frustration is relieved by defects, which enable the formation of branched networks and irregular bundles.
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