BY LISA COLEMAN
No. It's not Harry Potter who's wielding a new technology with "magic ability" called Pixie Dust; it's IBM.
The company is shipping hard disk drives using its new magnetic technology that promises to quadruple storage capacity within two years. Today, the new antiferromagnetically coupled (AFC) media (dubbed "Pixie Dust" by its creators) is being shipped in IBM's 2.5-inch Travelstar disk drives, which offer capacities up to 48GB and data densities to 25.7Gb per square inch.
Within one year, IBM expects to use AFC coating technology in server-class drives. By 2003, IBM expects to hit the 100Gb data density mark-far surpassing the superparamagnetic limit. IBM has engineered a way around that hurdle, which scientists theorize is a region between 20 to 40 billion bits per square inch, where magnetic regions on the disk become too small and cannot retain data.
Antiferromagnetically coupled (AFC) media increases areal density by using multiple magnetic layers that act in opposite directions, yet stick together through a thin layer of metal.
"It's a new kind of magnetic sandwich, or layer, on the surface of the disk, which will allow us to push past the physical limitation of the superparamagnetic effect," says Currie Munce, director of hard disk drive technology at IBM's storage technology division and director of storage systems and technology at IBM's Almaden Research Center.
IBM replaced the single magnetic layer used to record information on disks with a three-atom-thick layer of ruthenium, or Pixie Dust. The element, which is similar to platinum, is sandwiched between two magnetic layers. Ruthenium couples the top and bottom layers in opposite directions, according to Munce. "Its opposite direction coupling is a seemingly 'magic' ability and allows us to continue to push densities to higher levels," he says.
The unique opposing magnetic orientations make the entire multi-layer structure appear much thinner than it actually is. Therefore, small high-density bits can be written on AFC media and retain their magnetization due to the media's thickness. In addition to enabling much higher capacities, the technology requires less power and could help reduce cost per MB, says Munce.