Since IBM introduced the hard disk drive 50 years ago, the density of data storage has increased by 65 million times--with much of that rise coming in the past decade. Each data bit in the ferromagnetic layer that coats the tiny disks in computers, video game consoles and iPods has gotten ever smaller--now a mere 30 nanometers across--and closer to its neighbors.

Designers have predicted for years that the miniaturization will hit a fundamental limit determined by the superparamagnetic effect: as the bit becomes more minuscule, the atomic energy holding the magnetic orientation of the bit's atoms in place (which defines a digital state of 0 or 1) becomes so small that ambient thermal energy can destabilize it, thus corrupting the data. That day has finally come. The big drive makers, such as Seagate Technology and Hitachi, are already shipping hard drives with the new architecture.

This article was originally published with the title Going Vertical.

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