Fig. 1: Schematic representation of a racetrack wire. This consists of a stack of 45 layers, each only about a nanometer in diameter. The scheme shows only three of the 45 layers. Skyrmions (shown in blue) are created in this special material system behind the bottleneck created by the slots when strong current pulses are sent through the wire. The skyrmions can then be moved along with other weak current pulses for storage along the wire. The presence or absence of a skyrmion then encodes a bit "1" or "0". In the background a section of an x-ray hologram can be seen, as the researchers have recorded to depict the skyrmions. (Graphic: Moritz Eisebitt)

Save data in three dimensions

"Our data is in the cloud" - whoever says that sometimes forgets that the data is ultimately stored on hard drives, in large data centers of companies like Google and Facebook. The individual data bits are stored in the magnetization of thin magnetic films. The bits are written with a mechanically moving read / write head with magnetic field pulses on a fast rotating disk, the actual hard disk. In order to be able to store more data in the same space in the future, scientists are working on moving from this inherently two-dimensional storage method to a three-dimensional method. In such so-called racetrack memories, the bits should also be stored as magnetization patterns, but now in a wire-like structure. There they can be read and written like on a racetrack - hence the name - very quickly. In contrast to today's hard disks, the writing and shifting of the bits should only be done with the help of very short current pulses and therefore the use of moving parts should be avoided altogether. Since the racetrack wires, like many parallel straws, can be packed tightly in three dimensions, significantly higher storage densities would be possible.

A candidate for the representation of single bits are the nanometer-small vortices in the magnetization of the magnetic material, the skyrmions. They fascinate the researchers because they can be moved by electricity and are very stable. The presence or absence of a skyrmion would then represent bits "0" and "1" in the future. In order to produce individual skyrmions in a controlled manner, however, up to now very expensive equipment was necessary - the current research results show a new path here.