Nano-Scale Magnets For Petabyte Disk Drives

Scientists are building more useful magnetic materials from the atom up.
The chances are good that you think of photo-covered fridges when you hear the word "magnet." But in her lab at Brookhaven National Laboratory's Materials Department in Upton, N.Y., materials scientist Laura Henderson Lewis thinks of fantastically stronger, smaller materials levitating trains and shrinking data-storage devices.

Lewis, who studies nanocrystalline magnetic materials, builds magnets from the atom up. Most matter is made of chunks of material from 1 micron (a millionth of a meter) to 100 microns across. But Lewis works with magnets made of tiny crystals a mere 10 to 100 nanometers (or billionth of a meter), which makes her magnets much more versatile.

Nanocrystalline magnets can be custom-built far stronger and to more exacting specifications than standard magnets. They're already used in medical equipment, antilock brake sensors, and other devices. "They're more expensive, so they're reserved for the high-end issues where performance really outshines cost," says Lewis. They're also often used in data storage, where manufacturers can isolate each crystal to make sure individual magnetically recorded packets of data don't bleed into each other, causing loss of data.

In the future, as scientists learn more about how they can structure these materials, nanocrystalline magnets will become stronger, more precise, and more useful, particularly in data storage, where the size of storage media will shrink at the same time its able to hold more information. Thanks to more tightly packed crystals, these materials are expected to offer at least 10 times as much storage within a few years. They also might show up in tomorrow's transportation systems; nanocrystal magnets would be strong enough to levitate trains without the electrical demands and superconductivity of today's bullet trains.