By tweaking the formula for growing oxide thin films, researchers at the Oak Ridge National Laboratory achieved virtual perfection at the interface of two insulator materials.
This finding, published in the journal Advanced Materials, could have significant ramifications for creation of novel materials with applications in energy and information technologies, leading to more efficient solar cells, batteries, solid oxide fuel cells, faster transistors, and more powerful capacitors.
The atomic resolution Z-contrast images show individual silicon atoms bonded differently in graphene. (Photo by ORNL)
Electron microscopy at the Oak Ridge National Laboratory is providing unprecedented views of the individual atoms in graphene, offering scientists a chance to unlock the material’s full potential for uses from engine combustion to consumer electronics.
Graphene crystals were first isolated in 2004. They are two-dimensional (one-atom in thickness), harder than diamonds and far stronger than steel, providing unprecedented stiffness and electrical and thermal properties. By viewing the atomic and bonding configurations of individual graphene atoms, scientists are able to suggest ways to optimize materials so they are better suited for specific applications.
Researchers at Oak Ridge National Laboratory have reported progress in fabricating advanced materials at the nanoscale. The spontaneous self-assembly of nanostructures composed of multiple elements paves the way toward materials that could improve a range of energy-efficient technologies and data storage devices.
ORNL Materials Science and Technology Division researcher Amit Goyal led the effort, combining theoretical and experimental studies to understand and control the self-assembly of insulating barium zirconium oxide nanodots and nanorods within barium-copper-oxide superconducting films.
Not only is Oak Ridge National Laboratory’s Titan the world’s fastest supercomputer, it is also ranked third in energy efficiency. (Photo courtesy of ORNL)
Not only is Oak Ridge National Laboratory’s Titan the world’s most powerful supercomputer, it is also one of the most energy-efficient.
Titan came in at number three on the Green500 list. Organized by Virginia Tech’s Wu-chun Feng and Kirk Cameron, the list takes the world’s 500 most powerful supercomputers—as ranked by the Top500 list announced Monday—and reorders them according to how many calculations they can get per watt of electricity.
The Titan supercomputer at Oak Ridge National Laboratory is now ranked as the world’s fastest. (Photo courtesy of ORNL)
The No. 1 ranking for the new Titan supercomputer, designating it as the most powerful in the world, was clearly appreciated in East Tennessee on Monday.
But even as they celebrated a return to the top spot, scientists at Oak Ridge National Laboratory, where the giant computer is based, said they are focused more on research than rankings.
“We love being No. 1,” said Bronson Messer, acting group leader for scientific computing at the National Center for Computational Science at ORNL. “It’s great recognition. But what really matters is what science will do with the machine.”
Nano-ribbons of silicon configured so the atoms resemble chicken wire could hold the key to ultrahigh density data storage and information processing systems of the future.
This was a key finding of a team of scientists led by Paul Snijders of the U.S. Department of Energy’s Oak Ridge National Laboratory.
The researchers used scanning tunneling microscopy and spectroscopy to validate first principle calculations—or models—that for years had predicted this outcome. The discovery, detailed in New Journal of Physics, validates this theory and could move scientists closer to their long-term goal of cost-effectively creating magnetism in non-magnetic materials.
“While scientists have spent a lot of time studying silicon because it is the workhorse for current information technologies, for the first time we were able to clearly establish that the edges of nano-ribbons feature magnetic silicon atoms,” said Snijders, a member of the Materials Science and Technology Division.
The surprise is that while bulk silicon is non-magnetic, the edges of nano-ribbons of this material are magnetic.
Snijders and colleagues at ORNL, Argonne National Laboratory, the University of Wisconsin and Naval Research Laboratory showed that the electron spins are ordered anti-ferromagnetically, which means they point up and down alternatingly. Configured this way, the up and down spin-polarized atoms serve as effective substitutes for conventional zeros and ones common to electron, or charge, current.
“By exploiting the electron spins arising from intrinsic broken bonds at gold-stabilized silicon surfaces, we were able to replace conventional electronically charged zeros and ones with spins pointing up and down,” Snijders said.
This discovery provides a new avenue to study low-dimensional magnetism, the researchers noted. Most importantly, such stepped silicon-gold surfaces provide an atomically precise template for single-spin devices at the ultimate limit of high-density data storage and processing.
“In the quest for smaller and less expensive magnets, electro-motors, electronics and storage devices, creating magnetism in otherwise non-magnetic materials could have far-reaching implications,” Snijders said.
The paper is available online at http://iopscience.iop.org/1367-2630/14/10/103004. This research was funded by DOE’s Office of Science, the National Science Foundation, and the Office of Naval Research.
This work was supported by the Center for Nanophase Materials Sciences at ORNL. CNMS is one of the five DOE Nanoscale Science Research Centers supported by the DOE Office of Science, premier national user facilities for interdisciplinary research at the nanoscale.
Together, the NSRCs comprise a suite of complementary facilities that provide researchers with state-of-the-art capabilities to fabricate, process, characterize and model nanoscale materials, and constitute the largest infrastructure investment of the National Nanotechnology Initiative. The NSRCs are located at DOE’s Argonne, Brookhaven, Lawrence Berkeley, Oak Ridge, and Sandia and Los Alamos national laboratories. For more information about the DOE NSRCs, visit http://science.energy.gov/bes/suf/user-facilities/nanoscale-science-research-centers/.
