LAUSANNE, SWITZERLAND – The sticky point about magnets is that they aren’t all magnetic, it turns out. An EPFL research team working under Henrik Ronnow has found a magnet that’s not magnetized, with implications for hard disk technology.
The basic research findings by the Lausanne team could help hard disk developers, who are working with magnetic properties at increasingly miniaturized scales, to push through to the next level of miniaturization. EPFL says in a press release 29 June, citing Ronnow:
“Data are stored in binary form by changing the magnetic polarity of an area of the disk. With miniaturization, however, the problem is that sectors close to one another can influence each other, and spontaneously change polarity. The data would then be lost. ‘With these special materials, miniaturization could continue; each sector of the disk could be one of these magnetization-free pairs. The probability that the magnetic field of one atom would influence the magnetic field of its neighbor is practically nil.’ There’s just one intrinsic obstacle that must be overcome, however, with these materials: creating a read/write head sensitive enough to decode a magnetic field that is, by definition, extremely weak.”
For those whose high school physics left them with the idea that one stable thing in the universe is the magnet, here’s the updated version of that lesson. A compass needle is made up of a number of magnetized elements that arrange themselves into a crystalline network. “Like so many miniature compasses, the magnetic fields of all these atoms all point in the same direction. Trapped in this structure, the magnetic field of each atom adds itself to that of all the other atoms, producing the total magnetic field of the compass. In the material studied at EPFL, the atoms are arranged in pairs in a very particular way: the magnetic field of one atom is the opposite of that of its neighbor. As a result, the total magnetic field of each pair is practically nil. The entire material thus loses its magnetization.”
How the team discovered this: EPFL press release