To create these vortices, Norbert Martin places tiny glass spheres with a diameter of 0.30 thousandth of a millimeter (300 nanometers) on top of a thin magnetic layer. Under specific conditions, all of these glass spheres arrange next to each other and therefore form a mask of tiny hexagons with small gaps. When the scientists direct argon ions at this layer, these atomic and electrically charged projectiles penetrate the gaps between the glass spheres and force particles out of the magnetic layer located under the gaps. The array of the glass spheres, thus, functions as a mask: One magnetic disk remains below each individual glass sphere, while the magnetic layer under the gaps erodes. During the bombardment, though, the argon ions remove material from the glass spheres which, according to that, continuously decrease in size. At the end of the process the diameter of the glass spheres is only 260 nanometers, instead of the original 300 nanometers. This permits the argon ions to reach also areas which are located further inside the magnetic disks that are emerging beneath the glass spheres over time. Because the time of bombardment is shorter in these places, less material is removed on the inside. The desired slanted edge is therefore created virtually on its own.
The original article is published in Advanced Functional Materials, Volume 21, p. 891 (DOI: 10.1002/adfm.201002140). The results were compiled primarily at the Leibniz Institute for Solid State and Materials Research (IFW) Dresden where both scientists worked prior to joining the HZDR. Both institutes have been cooperating for many years in the field of magnetic research.
|Contact: Dr. Christine Bohnet|
Helmholtz Association of German Research Centres