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Will a blast of light speed up your disc?

作者:袁跋苦    发布时间:2019-03-08 04:17:14    

By Charles Seife A LASER will speed up your computer’s 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 “0” into a “1” 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’t budge the spins of the atoms in the iron-nickel layer. What you have to do is zap the nickel oxide with an ultraviolet laser. This disrupts its electrons and ruins the pinning effect. “It switches off the pinning field,” says Farrow. “When the pinning is lost, the spins respond and rotate to align with the applied field.” 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). “This is an interesting step,” says physicist Mark Freeman at the University of Alberta. “I can’t speak for whether it will be a competitive technique for storage, but I think it’s cool.” 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’s colleague Arto Nurmikko of Brown University in Providence, Rhode Island, says they are working on a way round that. “With additional experimental conditions, they remain indefinitely,” says Nurmikko,

 

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