IBM takes atomic approach to hard drive

There are 12 inches in a foot. There are 12 months in a year. And thanks to IBM, there are 12 atoms in a bit.

The company says it’s found a way of dramatically decreasing the space it takes to store computer data, raising the possibility of huge increases in storage capacity and utterly shattering at least one variation of Moore’s Law.

According to IBM, its five year project started by approaching the issue of data storage from a different perspective. At the moment it takes something in the region of a million atoms to store one bit of data (ie, either a 0 or a 1), a figures companies are constantly trying to shave down.

Instead IBM took a more fundamental approach, trying to figure out the lowest possible number of atoms that could store information. The obvious starting point was using a single atom held in one of two states, but it turned out that any grouping of less than a dozen atoms was unreliable as quantum effects meant data could be lost.

Achieving this in practical terms also involved a shift in tactics. In standard storage devices, the atoms are arranged in a ferromagnetic manner, meaning they all spin in the same direction. That has inherent limitations because you wind up with a magnetic field that causes more and more interference as the storage device becomes smaller.

The IBM team got round this with an antiferromagnetic arrangement, meaning each atom spins in the opposite direction to its neighbors.

The 12 atoms figure is somewhat arbitrary. In the final IBM experiment, it was able to stably store the bit of data by manually repositioning eight of the atoms with a scanning tunelling microscope (roughly equivalent to partially rotating a pool ball with a cue tip.) This experiment used iron atoms on a copper nitride surface, and it’s possible other materials could work more efficiently.

On the other hand, the experiment was carried out at 1 degree Kelvin (minus 272 Celsius) and the storage became unstable at 5 degrees Kelvin. The researchers believe it would take around 100 to 150 atoms for the technique to work at room temperature.

That’s still up to 10,000 times fewer atoms than existing technology. IBM’s Andreas Heinrich has noted that an incredibly conservative estimate of being able to use 100 times fewer atoms in practice would make a 100TB hard drive viable.

There’s been talk of Moore’s law being “violated”, which is a little misleading. In its purest form, the “law” holds that the number of transistors that can fit on a particular size of circuit will double every two years. That’s largely proven accurate over the past 50-plus years. The concept has been adapted to other elements of computing, including hard drive capacity.

(Picture credit: IBM Research)

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