![]() ![]() “We found that by loading hydrogen into this structure we can reduce the gadolinium’s magnetic moment by a lot,” Huang explains. The change is sufficient to switch the net magnetic field orientation by 180 degrees - exactly the kind of complete reversal that is needed for devices such as magnetic memories. The balance between the two in the composition of the alloy determines the material’s overall magnetization.īut the researchers found that by using a voltage to split water molecules along the film’s surface into oxygen and hydrogen, the oxygen can be vented away while the hydrogen atoms - or more precisely their nuclei, which are single protons - can penetrate deeply into the material, and this alters the balance of the magnetic orientations. In it, the two elements form interlocking lattices of atoms, and the gadolinium atoms preferentially have their magnetic axes aligned in one direction, while the cobalt atoms point the opposite way. The new system uses a film of material called gadolinium cobalt, part of a class of materials known as rare earth transition metal ferrimagnets. The findings appear in the journal Nature Nanotechnology, in a paper by postdoc Mantao Huang, MIT professor of materials science and technology Geoffrey Beach, and professor of nuclear science and technology Bilge Yildiz, along with 15 others at MIT and in Minnesota, Germany, Spain, and Korea. The discovery could usher in a new era of ferrimagnetic logic and data storage devices, the researchers say. Researchers at MIT and elsewhere have developed such a method, a way of rapidly switching the magnetic polarity of a ferrimagnet 180 degrees, using just a small applied voltage. But until now there has been no simple, fast, and reliable way of switching the orientation of these magnets, in order to flip from a 0 to a 1 in a data storage device. In principle, because of their magnetic properties are strongly influenced by external forces, ferrimagnetic materials should be able to produce data storage or logic circuits that are much faster and can pack more data into a given space than today’s conventional ferromagnets. As a result, the overall magnetic field they produce depends on the balance between the two types - if there are more atoms pointed one way than the other, that difference produces a net magnetic field in that direction. Less common are magnets based on ferrimagnetic materials, with an “i.” In these, some of the atoms are aligned in one direction, but others are aligned in precisely the opposite way. ![]() These materials form the basis for most of the data storage devices in today’s high-tech world. The north-south magnetic axes of most atoms in these materials are lined up in the same direction, so their collective force is strong enough to produce significant attraction. Most of the magnets we encounter daily are made of “ferromagnetic” materials. ![]()
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