More Memory
A new device uses heat to fit extra bits on a hard disk

Source: “Heat-assisted magnetic recording by a near-field transducer with efficient optical energy transfer”
William Challener et al.
Nature Photonics 3: 220-224

Results: Researchers at Seagate have developed a way to deliver targeted pulses of heat to the magnetic areas of hard-disk drives. The technology should make it possible to write up to 20 times more data to disks than is possible today.

Why it matters: Hard drives record data when a magnetic head moves across a disk coated with small grains that represent 1s or 0s, depending on their magnetic orientation. To cram more data onto these drives, researchers have been making the grains smaller and smaller. But grains made of conventional materials will become unstable if they’re too small, losing data when they experience small fluctuations in temperature. The new recording method allows the researchers to use materials that are more stable, packing more bits into a given area to increase data storage capacity. In addition to holding more data, the resulting hard drives could be more reliable.

Methods: Today’s magnetic heads can’t write data to the more stable recording media. Heating the grains solves this problem, but it’s been difficult to heat an area small enough to keep surrounding grains from being affected; no conventional lens can focus laser light onto such a tiny spot. The researchers accomplished this by focusing the light with a device called an optical antenna instead of a lens.

Next steps: The company hopes to reduce the concentrated spot of heat from 70 nanometers to 20 nanometers. The engineers are also developing a way to deliver laser light efficiently to the recording head.