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Posted: October 21, 2008
Tuning magnetic nanotubes
(Nanowerk News) One basic tenet of nanotechnology is that on the sub-microscopic scale, size matters. Magnetic nanostructures are no exception. German researchers have shown how the dimensions of tiny magnetic tubes affect their properties and could impact future data storage applications.
The "ones" and "zeros" on a computer hard drive are currently encoded by aligning tiny magnetic grains in the material over regions as small as a few 100 nanometers across. These regions cannot get much smaller, as the grains need a certain number of neighbors to maintain their alignment. The lower size limit, which defines the data storage performance, might be overcome by switching from grains to tubes. A tube's narrow geometry, which can be as little as 20 nanometers across, keeps the magnetic alignment relatively fixed, so a single tube could hold a single bit of data. When stacked side-by-side in an array, "the tubes have a very small footprint," says Julien Bachmann of Hamburg University.
Bachmann and his colleagues can make magnetic nanotubes of varying size using a technique called atomic layer deposition. Inside a pre-formed template, layers of magnetic material are added one at a time to make walls as thin as 4 nanometers. Among other results, the scientists found that the magnet moments within a tube interact with each other in different ways depending on the wall thickness.
At the AVS 55th International Symposium & Exhibition, Bachmann will discuss how this kind of information, although still in the research stage, could one day help engineers design nanotube geometries that are optimum for data storage, or for other possible applications in microelectronics and medicine.