A LASER will speed up your computer鈥檚 hard disc drive by a factor of 10, if
the latest research from IBM lives up to its promise.
Hard drives are notoriously slow. This is partly because the data are stored
by means of an external magnetic field. This reverses the spin direction of
atoms in the disc, flipping their magnetic fields to align with the external
field. This process effectively turns a 鈥�0鈥� into a 鈥�1鈥� on your hard drive and
normally takes about a nanosecond.
But now Robin Farrow of IBM in San Jose, California, and his colleagues have
come up with a faster method. The new technique uses a layer of iron and nickel
deposited on nickel oxide. Usually, all the spins of the iron-nickel layer align
in the same direction, pinned in place by the field of the aligned spins of the
top layer of nickel oxide atoms. Even a weak magnetic field won鈥檛 budge the
spins of the atoms in the iron-nickel layer.
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What you have to do is zap the nickel oxide with an ultraviolet laser. This
disrupts its electrons and ruins the pinning effect. 鈥淚t switches off the
pinning field,鈥� says Farrow. 鈥淲hen the pinning is lost, the spins respond and
rotate to align with the applied field.鈥� It turned out that the spins flipped in
just 100 picoseconds, about a tenth of the current time (Physical Review
Letters, vol 82, p 3705).
鈥淭his is an interesting step,鈥� says physicist Mark Freeman at the University
of Alberta. 鈥淚 can鈥檛 speak for whether it will be a competitive technique for
storage, but I think it鈥檚 cool.鈥�
But atoms in a permanent storage device, such as a hard drive, must stay
flipped around indefinitely. With the new technique, some soon flip back to the
original state. Farrow鈥檚 colleague Arto Nurmikko of Brown University in
Providence, Rhode Island, says they are working on a way round that. 鈥淲ith
additional experimental conditions, they remain indefinitely,鈥� says Nurmikko,
who won鈥檛 divulge details till the process is patented.