Traditionally hard-disk drives store data in a magnetic material, which is deposited on the surface of a spinning disk. Also, during manufacture the magnetic material is deposited as a thin film and information (as data) is written on the disk, by changing the magnetic orientation of distinct individual units of the material, known as "grains". The fabrication of a group of grains together make-up a region that can store a single bit. It is such a production procedure which has spearheaded the industry since the 1950s when the technology was originally invented. Subsequently hard-disk manufacturers have continually found ways to keep-on increasing the data storage capacity by reducing the area required to store a bit. Most recently this being by employing fewer and fewer clustered grains per bit. Please Note the increasing of data storage capacity is no dissimilar to the theory proposed by Gordon Moore - co-founder of Intel, Inc.
Nowadays the industry is rapidly running-up against limits to this strategy - partly, because the particles which magnetise become less stable when they are very small, a phenomenon known as super-para-magnetism. As stated by Currie Munce - Vice President of HGST Research - "If I take a permanent magnet and I make it small enough, it effectively becomes non-magnetic," In addition, there are also physical limits to how small the recording regions can be - as stated by Grant Willson, a materials science professor at the University of Texas at Austin - "If you continue to try to push these magnetised areas closer and closer together, they finally reach a point where they can feel their neighbors to such an extent they they have a tendency to flip over," Such a 'flip-over' causes detrimental data loss.
For decades researchers have known that so called 'nano-patterning' of a disk, whereby physically isolated nanoscopic magnetic dots make it possible to pack more information then applying the material as a continuous film. However, the commercialisation challenge remains into how to develop an economical-way to manufacture disks with precise nanoscopic patterns in the circular tracks needed for the recording head to do its work.
Interestingly the HGST researchers announced at last month's SPIE advanced lithography meeting that they had employed their proprietary nano-imprinting process to pattern a disk substrate with 10 nm wide dots, which were closely packed and in circular tracks. They demonstrated that a recording head can read and write information from these dots, and they recorded that their process could print 1.2 trillion "magnetic islands" per square inch, which is enough to store about a terabyte on a 2.5-inch disk, which is double the capacity of today's devices. Considering that the dots can be manufactured to even smaller dimensions - means that in theory the method could allow for several more generations of capacity gains.
Historically nano-imprinting first emerged in the mid-1990s, which consisted of applying a soft material to a surface and then literally 'stamping' it with a hard material covered by specific patterns. The resultant imprints help guide modification to the surface, such as etching or deposition of additional material. Next in the procedure is to remove the soft material, thus, leaving only the new designs on the original surface. The magnetic recording and semiconductor industries both view the technique as a highly promising solution - especially as to the puzzle of how to reliably manufacture structures and patterns smaller then ca. 20-30 nm.
To design their particular stamp - the HGST researchers employed molecules called block co-polymers, which can be precisely engineered to line-up in repeating patterns on a treated surface - a technique typically known as "directed self-assembly." As stated by a researcher (Munce) - "we think we can implement [the process] in manufacturing" The next stage for the HGST engineers is to focus on making the dots as small as physically possible, whereby Munce states "around 15 or 20 years from now they will run-up against another size limit." However, by then, as also stated by Munce, that provided several further refinements to the technology, "I may have brought myself another factor of 20 in capacity gains." Original article available here and Similar article available here.
As with research previously highlighted originating from A*STAR, IBM and other entities - DCN Corp finds the above milestone extremely proactive. Interestingly it is strongly believed DCN Corp can achieve the same nano-scale topology by homogeneously dip coating, thus, if you or your colleagues are interested in making the above a reality - please ensure to contact the company as soon as practicably possible.