A new method of writing data on hard disk drives could yield significant boosts in storage per square inch.
Hard drive density has reached a plateau in recent years because of the way write heads work. With current technology, write heads heat up individual bits to change their value, so the bits must be kept a certain distance apart. Otherwise, the write head could accidentally heat up surrounding bits, changing their value and ruining data. This issue is called superparamagnetism, and it limits current hard drives to two or three hundred gigabytes per square inch.
A paper in Nature Photonics, spotted by Ars Technica, describes another way. Researchers found that by combining two existing write methods, called thermatically-assisted magnetic recording (TAR) and bit-patterned recording (BPR), researchers have reached HDD densities of one terabit per square inch. That's not as good as current standards, which equate to roughly 2 terabits per square inch, but researchers say stability won't suffer even at five times the density of what they've achieved already.
TAR heats individual bits on a small-grain surface, and then cools the surface down once the data writing is complete. The problem with this method is that small-grain surface is not readily available, and you still have to keep bits far apart to prevent superparamagnetism. BPR separates writing onto "magnetic islands" that isolate bits even when densely packed, but the process requires specialized write heads to match each island.
A unique combination of the two solves both problems. Using lasers and plasmonics, researchers were able to concentrate heat to very small areas in a way that works with BPR's magnetic islands. The result is superior density without the need for specialized write heads.
It's not clear when this technology will reach the market, if ever, but it does suggest that a breakthrough in storage potential is on the horizon. Even if you're perfectly happy with a 250 GB drive, more capacity will be crucial, either at home or in the cloud, as the world's thirst for data grows.
