IBM sprinkles more Pixie Dust on HDDs
Five layer Ruthenium sandwich
IBM boffins have squeezed more areal density from its latest mobile hard drive, thanks to a liberal extra coating of Pixie Dust.
This is IBM's nursery school term for some home-grown data storage technology called antiferromagnetically-coupled (AFC) media. IBM first embedded the technology in hard drives last year, and this time around is improving its areal density properties - by 100 per cent - by adding another Pixie Dust layer.
The five layer "laminated Pixie Dust' sandwich makes its debut in the Travelstar 80GN, a new family of hard drives which hits the streets in January, 2003. It allows up to 70 billion bits of data to written on each square inch of disk space. Which is nice. IBM predicts that it will achieve 100 billion bit/sq in using Pixie Dust in 2003.
IBM's Pixie Dust is a three-atom thick layer of the element Ruthenium. The Ruthenium forces adjacent layers to orient themselves magnetically in opposite directions. The opposing magnetic orientations, IBM explains, make the multilayer structure appear much thinner than it actually is. So small, high-density bits can be written easily on AFC media, but they will retain their magnetisation due to the media's overall thickness.
And why is the Ruthenium sandwich needed to squeeze greater areal density. Well prior to its arrival, researchers predicted the potential degradation of data stored on disk when densities reached 20 to 40 gigabits per square inch - i.e. which is near the data density of today's products.
This is because of the "superparamagnetic effect" - when magnetic regions on the disk become too small they cannot retain their magnetic orientations - the data - over the typical lifetime of the product. ®
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