Imagine being able to store 25 full-length, DVD-quality movies on a disc the size of a quarter. That amounts to a data storage density of about 1.2 trillion bits per square inch. A recent development by University of Massachusetts researchers may someday enable consumers to do just that. The research is detailed in the Dec. 15 issue of the journal Science and is funded by a National Science Foundation "Partnership in Nanotechnology" grant, the Materials Research Science and Engineering Center, and the U.S. Department of Energy.
The UMass team, led by Mark Tuominen of physics and Thomas Russell of polymer science and engineering, specializes in nanofabrication - the science of developing devices and structures so small that they can only be seen with high-magnification electron microscopes or scanning-probe microscopes. Specifically, the researchers have invented a new technique for creating tightly-packed arrays of magnetic nanowires. Besides Tuominen and Russell, the paper's co-authors are UMass postdoctoral researcher Thomas Turn-Albrecht, UMass students Jorg Schotter, Gerd Kastle, and Nathan Empley, and IBM scientists T. Shibauchi, Lia Krusin-Elbaum, Kathryn Guarini, and Charles Black of the IBM T.J. Watson Research Center of Yorktown Heights N.Y. and Los Alamos National Laboratory, Los Alamos, N.M.
The project relies on self-assembling, nanoscopic, polymer scaffolds known as "nano-templates." The templates, which resemble highly-ordered honeycomb structures, enable the researchers to "grow" arrays of cobalt metal nanowires using a process called electrodeposition, Tuominen said. The scientists can fill microscopic tubes with metal, creating nanowires that are 14 nanometers in diameter - about 10,000 times thinner than a human hair. Such readily fabricated and well-controlled arrays of magnetic elements have great potential in magnetic data storage, the scientists say.
Specifically, the team induced a group of short copolymer nanocylinders to self-assemble within the polystyrene matrix. They exposed the structure to ultraviolet light and used a chemical rinse, which resulted in a thin polystyrene film riddled with regularly spaced pores. The scientists then used electrodeposition to grow metallic wires through the pores, yielding a densely packed nanoarray. The scientists point out that the polymer template fabricating technique is quite general and could also be used for fabricating other array devices with nanoscale dimensions. Or, the pores could also function as nanoreactors, holding catalysts for chemical reactions.
Mark Tuominen can be reached at 413/545-1944 or tuominen@physics.umass.edu.
Thomas Russell may be reached at 413-577-1516 or russell@mail.pse.umass.edu.
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Science