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Hitachi breakthrough promises 4TB drives by 2011

Hitachi has announced the smallest drive read heads to date, at 30nm and 50nm …

Hitachi announced today that it has developed the world's smallest hard drive read heads, and that it expects the new technique to eventually quadruple hard drive size within four years.

The company's new technology is called current-perpendicular-to-the-plane giant magneto resistive, or CPP-GMR. Current hard drives use tunneling magnetoresistance, or TMR, which allows drive heads to read data on tracks that are 70nm apart. Areal density at that point is approximately 200Gb per square inch. Increasing that density means laying data tracks closer to each other, which in turn requires a smaller read head. As a read head shrinks, however, electrical resistance and electrical noise both increase. According to Hitachi, researchers have predicted that attempting to increase areal density past 500Gb per square inch using TMR technology will be difficult, at best

Hitachi believes that the key to building drives that surpass the TMR's areal density limitations is the use of CPP-GMR technology, in which data is read from a perpendicular angle, rather than a parallel plane. Parallel plane implementations of GMR technology preceded the current TMR standard, and are what allowed for the tremendous boost in hard drive capacity from the late 1990s to early 2000s. The two scientists who independently discovered the phenomenon of giant magnetoresistance (Albert Furt and Peter Grünberg) were awarded the Nobel Prize for physics last week.

Eventual limitations in parallel plane GMR is what led to the development of TMR and perpendicular recording. The CPP-GMR standard is therefore something of a return to earlier manufacturing technology, but approaches the problem of shrinking read heads from a different angle.

Hitachi isn't the only manufacturer working on implementing CPP-GMR technology, but there's something of a disagreement over just how much life remains in TMR manufacturing. While Hitachi predicts that 500Gb per square inch is essentially the limit for TMR, other manufacturers, including Seagate, believe TMR could potentially be scaled up to an areal density of 1Tb per square inch. Hitachi isn't betting the farm on CPP-GMR—even as the company unveils plans for 50nm drive heads in 2009 and 30nm drive heads in 2011, it continues to work on improving drive density using TMR—but the corporation is obviously hoping that its early lead in announcing smaller drive heads based on the new standard will translate to greater market share over the long term.

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