January 13, 2012, 6:01 PM — I can't say I've ever really needed to know this, but, according to IBM researchers, storing a single bit of data on a disk drive requires one million atoms of magnetized storage medium.
The only reason it's important to know that now is that IBM's Almaden Research Center is touting a new approach to magnetic storage that requires as few as 12 atoms worth of medium to store a single bit of data.
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Existing magnetic storage media – hard drives, just to stick to one form factor – are designed with all the magnetic poles of all the atoms aligned in the same direction.
When they're exposed to a magnetic field, ferromagnetic materials like iron, nickel and other metals used in storage media line up and coordinate not only their magnetic poles, but the orbits of unpaired electrons as well.
The opposite condition – antiferromagnetism – in materials such as manganese oxide causes atoms to align head-to-foot so that the North magnetic pole of each atom seeks the South magnetic pole of another.
That focuses more of the magnetic field within the material itself. Because all the atoms expose the same magnetic pole in the same direction, the magnetic field in ferromagnetic materials reaches farther, and is easier to read than antiferromagnetism.
Similar magnetic poles push each other apart powerfully enough to levitate mag-lev bullet trains, or create more distance between atoms in a magnetic storage medium than would be the case if all those aligned magnetic poles weren't so repelled by one another.
The IBM Almaden center used the attraction of anti-ferromagnetic atoms to create a swathe of material with a much denser magnetic palette than typical ferromagnetic surfaces.
The atoms attract one another so closely and create a storage surface so dense that they can store more than 100 times as much data on the same number of atoms as more traditional media, according to Andreas Heinrich, the IBM Almaden researcher who led the research to develop the denser medium.
The paper describing their work was published in the current issue of Science.
The big problem with the new medium is the amount of work it takes to create it and temperature required to make it work.
The IBMers used a scanning, tunneling microscope to position and align individual atoms into the configuration they wanted.
They accomplished their storage goal – storing characters for IBM's slogan THINK – using an array of 96 atoms at a temperature close to absolute zero. At room temperature it would take about 150 atoms to accomplish the same goal, Heinrich said.
While denser storage media could make storage much more efficient and ultimately cheaper, the amount of effort and temperature required for this experiment don't encourage do-it-yourself imitators.
The equipment to see individual atoms – let alone manipulate them into useful shapes – costs far too much to be practical in anything but a research context.
The Almaden team is working on ways to make antiferromagnetic storage pracdital for mass manufacture, but are actually more interested in the potential to explore the quantum-mechanical behavior of small numbers of aligned antiferromagnetic atoms.
In very small numbers the atoms display some quantum mechanical characteristics, raising the possibility that the slot for each data bit could be both a "1" and a "0" simultaneously, paving the way for more reliable quantum computing materials, Heinrich told the NYT.
"It took a room full of equipment worth about 1 million dollars and a whole lot of sweat," to get the 96-atom configuration to work, Heinrich said. "The atoms are in a very regular pattern because we put them there. "Nobody knows how to make that cost effective in manufacturing…that’s the core issue of nanotechnology."
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IBM Almaden Research Center
