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It fell to the poet "to see the world in a grain of sand" (William Blake). It falls to modern physicists to see worlds in specks of matter far, far smaller than that.
In the irony of language, what's touted as "the next big thing" on the horizon of science and technology is a field where all the excitement is over the profoundly small.
So small, in fact, that the sizes so casually tossed around by those who work in the field defy belief. Building whole machines—and their spare parts—out of a few atoms?
It's happening.
Much of what would easily have passed for science fiction only 15 years ago is certified (read: marketable) fact today, thanks to a scientific gold rush called nanotechnology. The prefix "nano" says it all.
To the ancient Greeks, the word meant "dwarf." To physicists, technically it means "billionth." Things a billionth of a meter long, and less, thus belong to an exotic realm called the nanoscale, a cozy place—yet surprisingly roomy, as it turns out—that can be likened to nature's own workshop. It's a place where nothing less than the fundamental laws of physics and chemistry marry to produce all life and everything in it.
The nanoscale has suddenly become the bona fide final frontier for scientists the world over who are convinced that the best things in life are sure to come in the smallest of packages.
Count FSU's Prof. Stephan von Molnár as happily among them. Since 1994, von Molnár has led the university's Center for Materials Research and Technology, better known by its acronym MARTECH. Made up largely of physicists and chemists, the interdisciplinary group includes other researchers as well. Scientists with the National High Magnetic Field Laboratory, based three miles from central campus at the university's research park, are frequent MARTECH collaborators, as are various materials research specialists at the FAMU-FSU College of Engineering.
Von Molnár, (Ph.D. U-Cal Riverside) brought 28 years of research experience at IBM to campus. His IBM career coincided with the rise of semiconductor technology, which launched the silicon chip-based race to build ever-smaller computers. The field gave scientists and engineers their first taste of what's possible through intense research in miniaturization—the effort to build cheap, dependable devices of ever-shrinking dimensions.
As do many "nanoscientists"—the name now applies to researchers in fields ranging from aerospace engineers to molecular biologists (see box, page 28)—von Molnár credits a talk made in 1959 by the late theoretical physicist and Nobel laureate Richard Feynman with sparking his career interest in "dealing with tiny things," as he puts it. Feynman's prophetic address, entitled "There's Plenty of Room at the Bottom," is considered the field's seminal paper and is enshrined by dozens of websites devoted to nanoscience and nanotechnology.
"You read this paper, and all of a sudden you realize that this is what God knew," says von Molnár. "And the fact is, that's the driving force behind a lot of what we do."
Feynman may be the first non-biologist in fact who publicly drew analogies between manmade machines and the natural processes that drive the core engines of living organisms. Thanks largely to the advent of extremely powerful microscopes (whose development Feynman had stumped for) today's molecular biologists have expansive knowledge and understanding of how huge, hyper-complex molecules of proteins, Though he didn't dwell on the topic, Feynman also spoke of DNA's remarkable power in storing massive amounts of information about how to assemble a living, breathing life form. This almost spooky phenomenon presents the ultimate challenge to legions of scientists and engineers who labor to shrink memory devices in computers.
"We're working very hard to come even close to what is done apparently so effortlessly by our genes," says von Molnár.
But crude as it is by natural standards, the effort has nonetheless revolutionized society. Computers keep collapsing in size like a Chinese shell game, while their power steadily mounts. On the average, say computer trade magazines, the capacity of memory storage devices is doubling every 18 months. Is there an end-game here?
You bet, says von Molnár. But so far, no one seems to know exactly where the physical limits of memory storage technology—as it's presently configured—lie, he said. And that's precisely what he and his team of MARTECH researchers are trying to find out.
In trying to squeeze more memory into smaller spaces, scientists are headed toward a brick wall in the two-dimensional world that still defines memory storage technology, says von Molnár and Peng Xiong, his collaborator at FSU. Xiong (pronounced "SHIONG") is a specialist in designing super-fine nanostructures (see box, page 30). Basically, magnetic particles—individual bits of matter that hold the all-important magnetic orientation that collectively constitute words, numbers and images—are crammed together in the highest numbers possible in the least amount of space on the surface of recording media. Such crowding is mainly limited to the size of each particle—the smaller the particles, the higher the density, and thus the more useful the computer—at least up to a point. But particles can get so tiny and crowded that they fall victim to curious forces that pervade the nanoworld, says Xiong. "When you make things really small, other effects, like quantum mechanical effects, come into play," he said. As particles reach the vanishingly small sizes demanded by industry they become thermodynamically unstable and begin to lose their magnetic integrity. In other words, the laws that govern how a magnet normally works no longer apply and any stored information is in danger of getting erased. Physicists have a name for the phenomenon—it's called the superparamagnetic limit and it's a wall that the corporate world annually spends large sums in R&D trying to climb. (The federal government is highly interested in the phenomenon as well—much of MARTECH's work is supported by the National Science Foundation and the Office of Naval Research.) "The question is, how small can you make a magnetic particle so that it still knows how to behave like a magnet?," says von Molnár. The short answer is, a whale of a lot smaller than what is now commercially available. The MARTECH team has proven that despite physical limits imposed by arranging magnetic particles in two dimensions (length and width only), there's still a considerable leap possible through the manufacture of tinier particles. Last year, von Molnár's team succeeded in building what for a time stood as the smallest magnetic particles ever made. Some of these minuscule clusters of iron atoms are so small that roughly 100 billion of them can fit inside a square inch. The MARTECH particles, which in reality are tiny bar magnets standing on end, average about nine nanometers (nine billionths of a meter) in diameter, which works out to be the thickness of about 30 atoms of iron. Under testing, these "nano-pillars" (they stand between 150 and 200 atoms tall) turned out to be hardy magnets capable of rapid switching of polarization from "up" to "down" (or "0" or "1" in the binary language of computers), the signature of a durable memory unit capable of storing a single bit of information. MARTECH scientists have developed a technique to produce and arrange the particles in any configuration they choose, and are developing unique methods to measure the magnetic properties of individual particles, something not commonly done. "At this scale I think it's fair to say we understand more about how these magnetic particles behave than just about any other group I know," von Molnár said. Just this past May, IBM announced it had made a high-density array of even tinier particles, in fact roughly half the diameter of those built by MARTECH. In a highly controlled lab experiment, company engineers found a way to make special alloys self-assemble into thickets of particles up to 10 times the density of the MARTECH array. These ultra-dense arrays showed densities up to and exceeding 1,000 billion particles (a trillion) per square inch with no apparent loss in magnetic properties. While remarkable, this achievement came about by tweaking the formulas of complex alloys used in making the particles and using other technical tricks, rather than through a revolutionary breakthrough in beating the superparamagnetic limit. Still, IBM's success, along with MARTECH's, demonstrates the feasibility of profoundly increasing the density of memory particles on devices now on the market, says von Molnár. Today's best off-the-shelf hard drives, for example, sport about 14 billion bits (or 14 gigabits) of memory per square inch, a density that translates into 32 gigabytes of memory on a laptop computer's hard drive—reportedly enough space to hold all the text in a stack of documents more than a mile high. Industry moguls already are giddy with the thoughts of building a laptop with enough memory to hold all the information in the Library of Congress. But it's inevitable that the laws of physics will eventually shut things down for good in the two-dimensional world, says von Molnár. And when the transition to 3-D, cube-like memory devices comes—as many researchers believe is imminent—some of those same laws will conspire to slow progress in similar fashion, he says. Thus the reason for stepped-up basic research in all areas of nanoscience where immense problems stand between the promise of nano-technology and reality. Collaboration with other research groups is the key, particularly for comparatively small programs like MARTECH, says von Molnár. Since its beginning in 1984, MARTECH has maintained close ties with materials scientists and engineers at the University of Florida, which runs the most comprehensive materials research program in the state. With UF scientists, Von Molnár, Xiong, and Zachary Fisk, a physicist in experimental materials science with the National High Magnetic Field Laboratory, are pursuing a large-scale joint research effort to design and build whole new classes of nanoscale electrical components, quite possibly based on a new technology called spintronics. Ushered in by recent discoveries about how the spin of electrons—as opposed to their charge—can be used to provide new functionality in electronic devices, spintronics is a red-hot topic in nanotech research these days. By exploiting the electrons' spin characteristics, researchers see the possibility for orders of magnitude advancement in building tinier and faster computer chips. Such breakthroughs may prove useful in unlocking some of the sturdiest secrets in the nanoworld, perhaps even some of those Richard Feynman mused about 41 years ago about how nature works. "Since 1959 we've been stuck in a two-dimensional world, trying to do replicate what nature does in three," muses von Molnár. Confessing no particular religious proclivities, he marvels at even the simplest biological interaction, a phenomenon that easily puts his work in humbled perspective. "What we do is great fun. But you realize all of a sudden that, boy, no matter how much we learn there's something there that will remain an enormous challenge forever." |
for example, push and pull hundreds of molecules and useful chemicals through a cell's labyrinthine, wet machinery.