An approach called 3D Towers is believed to reach to a density level well beyond 1 Tb per square inch.
The original Winchester magnetic recording technology was generally believes to hit a density of about 250 Gb (per square inch), but the move to perpendicular magnetic recording open the way to about 1 Tb, which will be reached with two to three years, according to industry expectations. At that point, the hard drive industry may have to move to further enhancements, such as heat-assisted recording technologies.
However, it appears that scientists have found another way to avoid the expensive move to heat-assisted approaches one more time. Spintec demonstrated "several magnetic layers" to move beyond today's PMR hard drives.
"Our new approach involves using bit-patterned media, which are made of arrays of physically separated magnetic nanodots, with each nanodot carrying one bit of information," said Jerome Moritz a researcher with Spintec. "To further extend the storage density, it's possible to increase the number of bits per dots by stacking several magnetic layers to obtain a multilevel magnetic recording device." From the press release:
"Moritz and colleagues were able to demonstrate that the best way to achieve a 2-bit-per-dot media involves stacking in-plane and perpendicular-to-plane magnetic media atop each dot. The perpendicularly magnetized layer can be read right above the dot, whereas the in-plane magnetized layer can be read between dots. This enables doubling of the areal density for a given dot size by taking better advantage of the whole patterned media area."
The researchers released an image of two-bit-per-dot patterned media, but there was no information when such storage media could actually be produced.