Less Means More in Nano-Particles Research

  • October 5th, 2002

by Elizabeth M. Smith

Drs. J.W. Harrell (left) and Dave Nikles research ways to store more data in less space.
Drs. J.W. Harrell (left) and Dave Nikles research ways to store more data in less space.

If less is more, researchers in The University of Alabama’s Center for Materials Information Technology, or MINT, have struck gold in their attempts to discover how to store greater amounts of data in smaller storage spaces.

MINT is a multidisciplinary research program that focuses on developing new materials to advance current data storage. One major emphasis is on materials for magnetic heads and media. These are key components in high performance information storage systems such as computer hard disk drives, audio and videotape.

Twenty-two faculty from seven academic programs in the College of Engineering and the College of Arts and Sciences make up the center. Its mission is to perform world-class research, educate students and serve as a resource and communication channel for the information storage industry.

In August, MINT was selected for the third time as a National Science Foundation Materials Research Science and Engineering Center. In 1994, UA became the first such NSF center in the South and is now one of only 30 nationwide.

“Technologically, the goal is to develop materials that will sustain larger and larger storage densities,” said Dr. J.W. Harrell, professor of physics and astronomy in the College of Arts and Sciences. “Magnetic media consists of thin films with small particles or grains that act as magnets. For storage densities to increase, these grains must get smaller.”

Side-by-side magnetized grains will allow for greater capacities in storage.
Side-by-side magnetized grains will allow for greater capacities in storage.

That’s where the research comes in. Current storage densities for state-of-the-art technology are 30-40 Gigabits/square inch. Grain sizes in current state-of-the-art media average about 10 nanometers or 10-9 meters. A nanometer is a billionth of a meter, and it takes a million of them to span a grain of sand. Storage densities have been increasing at a phenomenal rate since the invention of the hard drive nearly 50 years ago and currently are doubling each year. As storage densities grow, the particle sizes must shrink so that the medium will hold more particles and store more data.

“At some point, if we make these grains too small they become thermally unstable,” Harrell said. “The magnetization no longer remains fixed in a single direction because of temperature effects.”

This temperature instability is called super-paramagetism.

“We have to figure out a way to have very small particles that are thermally stable,” said Dr. Dave Nikles, professor of chemistry at MINT in the College of Arts and Sciences. “So what we want to do is move to a magnetically more stiff material than the current materials used. One material with very high magnetic anisotropy is iron platinum.”

In order to improve the storage densities of these materials, the magnetic grains also need to be uniform in size. “If you make the sizes more uniform you can get closer to the superparamagnetic cliff where the magnetization becomes unstable,” Harrell said.

Nikles is working on synthesis technology, first reported by IBM about two years ago, and enables uniformly sized nano-particles of iron platinum to be made.

“Because they’re uniformly sized and made with a non-magnetic coating that is made in solution, it is possible for them to self-assemble into a highly ordered particle array,” Nikles said.

But they’re still superparamagnetic. So what Harrell and Nikles want to do is change the particles into a high anisotropy phase that would allow a 3.5 nm particle to be thermally stable for more than 10 years.

“And theoretically, if you could store a single bit per particle, in an ordered array, you could achieve 1,000 times greater storage density than is available today,” Harrell said.

The nano-particles project has industry interest from IBM, Seagate, Fujitsu and Hitachi-Maxell. The professors stress that there are no guarantees their research will become an industry product.

“Because we interact with these companies we have a good idea of what fundamental discoveries to science problems have to be made in order to make this commercially viable,” Nikles said. “There’s a limit to what a university can do and can afford to do. And at some point the companies have to decide whether it makes sense to take the technology inside the company.”

Nikles said that companies hire the highly trained experts in these materials, including UA students and graduates. Several graduates are presently working in Silicon Valley. One current graduate student recently finished a nanoparticles internship at Seagate.

“This is an indication that companies are interested in our research,” Harrell said. “If they weren’t interested in it, they wouldn’t be talking to us.”

The University of Alabama, part of The University of Alabama System, is the state’s flagship university. UA shapes a better world through its teaching, research and service. With a global reputation for excellence, UA provides an inclusive, forward-thinking environment and nearly 200 degree programs on a beautiful, student-centered campus. A leader in cutting-edge research, UA advances discovery, creative inquiry and knowledge through more than 30 research centers. As the state’s largest higher education institution, UA drives economic growth in Alabama and beyond.