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Could the average computer hard drive soon be able to store the equivalent of over 80 DVD-Audio discs or 600 CDs? Last week, IBM announced that it is using just a few atoms of what it has termed "pixie dust" to push back the data storage industry's most formidable barrier, and will effectively quadruple disk drive densities in the next two years.

In the past decade, the data density for magnetic hard disk drives has increased at a rapid pace, first doubling approximately every 18 months and then, since 1997, doubling on average once a year (which is much faster than the vaunted Moore's Law for integrated circuits.) But conventional wisdom held that the designers were accelerating toward a barrier that could suddenly halt further progress. When magnetic regions on the disk become too small, they cannot retain their magnetic orientations, which is how they store data over the typical lifetime of the product. This is called the "superparamagnetic effect," and experts have long predicted it would appear when densities reached 20 to 40 billion bits (gigabits) per square inch, which is near the data density of current products.

IBM says that scientists in the company have now overcome this barrier using a three-atom-thick layer of the element ruthenium, a precious metal similar to platinum, sandwiched between two magnetic layers. The company reports that, when they discovered that only a few atoms could have such a dramatic impact, their scientists began referring to the ruthenium layer informally as "pixie dust."

IBM explains that this approach is known technically as "antiferromagnetically-coupled (AFC) media" and adds that the new multilayer coating is expected to permit hard-disk drives to store 100 billion bits (gigabits) of data per square inch of disk area by 2003. The company adds that at these densities, 400GB hard drives in desktop computers and 200GB drives in portables will appear in the next two years.

Describing how AFC media works, IBM says that the ultra-thin ruthenium layer forces the adjacent layers to orient themselves magnetically in opposite directions. The opposing magnetic orientations make the entire multilayer structure appear much thinner than it actually is. "Thus small, high-density bits can be written easily on AFC media, but they will retain their magnetization due to the media's overall thickness," says the company.

In a statement describing the implications of the new technique, IBM says that "for consumers, increased data density will help hasten the transition in home entertainment from passive analog technologies to interactive digital formats. The increasing data densities enabled by AFC media are expected to simplify processes for storing consumers' rapidly growing volumes of digital data, accelerate an industry trend toward smaller disk-drive form factors that consume less energy, and stimulate the creation of new and more capable digital-media and data-intensive applications."

New hard-disc audio recording and playback devices have appeared in recent months, including Lydstrom's SongBank SL CD Memory System and Linn's Kivor. Also affected will be the professional audio recording industry which has been quickly transitioning to hard-disc–based, higher-resolution recording technologies for studio and remote applications.