Itsy-Bitsy Bits

January 15, 2012

Magnetic storage media have been around, in various forms, about as long as we’ve had computers.   Magnetic tapes have long been used for storage of really large data sets and for backups.  Back in the days of the System/360, a common IBM hard disk drive (DASD, Direct Access Storage Device, in IBM parlance) was about the size of domestic washing machine.  Floppy disks started out as 8-inch monsters, even before the introductions of the PC; they were used, for example, in dedicated word processors from Wang and IBM back in the late 1970s.   In the PC world, we first had 5.25-inch and then 3.5-inch floppies, and we still have our smaller, faster, and much more capacious hard disks.

Now, according to reports at Technology Review and the New York Times, researchers at IBM’s Almaden lab have developed a new type of magnetic storage material that is dramatically more compact than existing technologies, using only a dozen atoms per bit.

The smallest magnetic-memory bit ever made—an aggregation of just 12 iron atoms created by researchers at IBM—shows the ultimate limits of future data-storage systems.

By comparison, the highest-density magnetic storage devices made today use ~1 million atoms per bit.  The research is reported in the current issue of Science [abstract].  The technology is not quite ready to be included in your next laptop or smart phone.  It only works at very low temperatures (< 5K), and can only retain the data stored for a few hours.  Researchers feel that this can be improved by using a slightly larger number of atoms, ~150, but there is still no scalable method of manufacturing the material.

Nonetheless, the work is of great interest because it shows the possibilities for aggressive use of nanotechnology.  The experimental device is assembled using a scanning tunneling electron microscope (invented in the early 1980s at IBM Zürich) to place individual iron atoms in an anti-ferromagnetic alignment.  In conventional ferromagnetic materials, like the magnetic coating on disk platters, or the magnet on your fridge, the magnetic spins of individual atoms are aligned; this can lead to instability when components are made smaller.  The new material does not have this alignment, so some degree of stability can be achieved with a tiny amount of material.

It’s too soon to say for sure that this approach will produce a new type of computer storage; but we are approaching the physical limits of what can be done with silicon fabrication technology, so it’s good to see new approaches being explored.

Update Sunday, 15 January, 17:05 EST

Wired also has an article on this research, complete with an image of a byte of memory in the new material, with eight little 12-atom clumps.

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