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Revolutionary Magnetic Experiment Promises Better Hard DrivesNobel prize winners reveal their secret |
By Gabriel Gache, Science News Editor
20th of December 2007, 15:52 GMT
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The experiment for which Albert Fert and Peter Grünberg received the Novel Prize, for their new discoveries in the field of magnetism, concentrates mostly on the study of magnetic cores on the nanoscale, which seem to present extremely stable magnetization, which could potentially be used in the developing of the future non volatile magnetic memory.
The magnetic cores only 10 nanometers across are located in magnetic vortices that have been studied for only a few years, since they were discovered in extremely small ferromagnetic discs having a diameter of only a few micrometers, which exhibit a core feature only about 20 atoms across that presents a perpendicular magnetization. While applying a magnetic
field to the magnetic vortex, it is pushed away from the center of the ferromagnetic disc, and it starts rotating either clockwise or counterclockwise when the magnetic field is suddenly being removed, following a spiral trajectory as it regains its position, pointing towards the center of the disc.
Depending on the pointing direction of the magnetic core, in the center of the magnetic vortex, it can present four movement scenarios, whether rotating in one way of the other, or in a combined manner with an up or down motion perpendicular to the magnetization of the magnetic core. However, this behavior seems to be also available for a so-called anti-vortex, thus the two scientists started experimenting with a formation consisting of two vortices, between which there is a, anti-vortex placed.
However, while experimenting with such structures that are subjected to short magnetic pulses, the physicists observed that, contrarily to the general belief that the magnetic field of the vortices would annihilate with the anti-vortices, making a short analogy to the particle-antiparticle interactions from quantum physics, they instead formed a micromagnetic unit, named a cross-tie wall.
This peculiar behavior raised some serious questions, regarding how do the magnetic vortices interact with each other, in order to influence the overall dynamic of the structure or the arrangement of the cores, respectively whether the vortices and their counterparts repel each other, or attract each other. Furthermore, the spiral motions of the cores and the over all cross-tie wall also needed to be addressed.
Albert Fert and his colleague were the first ever to experimentally view the spiral motion of the magnetic vortex, and to answer all the previous questions related to the observed effects. They also represented the first team that showed the true orientation of the three magnetic cores, by studying their movements.
To continue their work in the study of the magnetized nano cores and vortices, the team is currently attacking the possibility of creating a single anti-vortice, and studying its magnetization dynamics.
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