Researchers change direction magnetic field of light without heat




Researchers at the Radboud University have shown that it should be possible in the future, the spins of iron atoms as to match with light that the magnetic poles can be reversed. If successful controlled, which saves heat in magnetic storage.

Radboud University Nijmegen logo The discovery was made by the same group of researchers already demonstrated in 2007 that fast laser light pulses magnets can reverse the polarity by very local, temporary heating. Johan Mentink, one of the authors of the new article Wednesday in Nature Communications published, says that when the material used not actually consisted of only two magnets: an alloy of gadolinium-iron-cobalt. Gadolinium is then the one magnetic material and the iron-cobalt alloy, the other.

“Normally those materials connected so strong that you do as a magnet can see. With the laser pulse were the materials are placed in the” war. “The internal forces in the magnet then ensure that the system reaches a new ground state by . himself to poles Then we thought: we can not directly address these internal forces, then reheat unnecessary “.

The latter indeed seems to be able to: directly with light, the internal forces, the so-called quantum mechanical Exchange interactions that are responsible for the magnetism itself, to change. There continue to be used laser pulses, but which heat the material now used for the examination is not, as this transparent material, iron oxide, the laser does not absorb, and therefore it does not heat up. “We have now got to light a handle to the exchange interaction of the forces that influence the origin of magnetism, direct. What we want to do in the future, those forces is changing so much that the magnet completely confused , whereby as with the rapid heating, reverse polarity is possible, “said Mentink.

One of the reasons Mentink cites where basic research ever possibly find practical use, it is in magnetic storage. Mentink “There is already evidence that switching to flash more energy than it takes turn with light If you could count how many write one bit cost of energy, that would be for laser induced switching have been less than what flash now. cost now is about one nanojoule per bit in flash With us it will even 10 femtojoule cost, though there are very large caveats to:.. with flash turn anything around and in a hard disk or a current hard drive will cost between. 10 and 100 nanojoule per bit. ”

Yet research has long is being done at other ways of magnetism influence in hard drives. Mentink says that Seagate in a while is engaged in heat-assisted magnetic recording. In addition, a laser pulse is used to heat the material and to make it easier to write to an external magnetic field. “We say: we only need a laser pulse on the write head and no small bobbin.”

With the increasing surface density of making the hard disk drives of the current technology is against the so-called super-paramagnetic limit, thereby making an increasingly large magnetic field is needed. “If you then switch to a fundamentally different technique, as in our case with the laser, there is no heat and magnetic field anymore.”

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