Skyrmions are three-dimensional structures around one hundred nanometers in size that occur in magnetic materials. They resemble small coils: atomic spins that arrange themselves in closed vortex structures. Skyrmions are topologically protected, i.e. their shape cannot be changed, and are therefore considered to be energy-efficient data storage devices.
Using soft X-rays, German researchers from the Max Planck Institute for Intelligent Systems (MPI-IS) in Stuttgart, together with Chinese researchers, were able to create individual skyrmions in a magnetic layer for the first time. In numerous experiments, they showed that a bundled soft X-ray beam with a diameter of less than fifty nanometers can produce a magnetic vortex of one hundred nanometers, the smallest possible size. The atoms responsible for the magnetism can be directly excited by a resonant effect. Thanks to the research work, practically anyone can now use an X-ray beam to write a wide variety of skyrmion arrangements in magnetic layers.
The results are particularly relevant for the development and production of spintronic data carriers that store information in skyrmions. They are considered to be very energy-efficient and less susceptible to interference. But only if skyrmions can be written precisely and accurately, and this has now become possible for the first time, can this development take its course. The aim is for X-rays to be used in future as a tool to determine or write the arrangement of magnetic structures.
To make skyrmions visible, the researchers use the scanning transmission X-ray microscope "Maxymus", a high-resolution X-ray microscope located at BESSY II, the synchrotron radiation source of the Helmholtz-Zentrum Berlin in Adlershof. The microscope is like a camera: it tracks in slow-motion films how the structure in materials changes at the size of just a few nanometers.
