DOI: 10.1038/s41567-025-02873-1
"With our results, we are adding another chapter to the still young field of skyrmion research," explains Harald Giessen , head of the 4th Physics Institute at the University of Stuttgart, in whose working group the success was achieved. The team provided evidence for so-called skyrmion pockets of light on the surface of a metal layer.
Skyrmions are a mathematical description for vortex-like structures in order to better understand fundamental physical relationships. In recent years, this theoretical concept has already been confirmed experimentally in very different areas, including in magnetic solids and on material surfaces. The Stuttgart working group has now investigated whether it can make light that falls on the structured surface of a thin layer of gold behave like skyrmion pockets that obey certain symmetries. These pockets consist of skyrmions that are located in a larger skyrmion. For their experiment, the participants applied fine grooves in the shape of two twisted hexagons to the gold surface, each of these hexagons generating a skyrmion light field.
"We then observed a superposition of two skyrmion light fields, from which the skyrmion pockets formed," notes Julian Schwab, first author of the publication and doctoral student in Giessen’s research group. What’s more, depending on how far the researchers twisted the light fields against each other, they were able to gather a different number of skyrmions in these skyrmion pockets. In other words, the researchers can manipulate light fields in a targeted manner, giving them shapes that do not usually occur. The Stuttgart team collaborated with a working group from the University of Duisburg-Essen to provide experimental evidence and with a working group from the Technion in Haifa to describe the phenomenon theoretically.
So far, this is all still basic physics. But: these light field skyrmions exhibit extraordinary properties - which naturally also stimulates the imagination of researchers with regard to possible technical applications. However, whether the gold layer used by the Stuttgart team is suitable for this purpose has not yet been researched. "If someone succeeds in finding a suitable material, the concept we demonstrated could be used in microscopy," says Giessen. It could then be possible to achieve such high resolutions with special microscopes that would actually be impossible due to the wavelength of the light used alone.
The 4th Physics Institute concentrates on research in the field of ultrafast nano-optics. On the one hand, the interactions of light with structures on a sub-micrometer scale are studied. On the other hand, the fundamentals and applications in the field of ultrashort laser pulses are investigated.
You can find out more about research at the 4th Institute of Physics on the University of Stuttgart website.
Julian Schwab, Alexander Neuhaus, Pascal Dreher, Shai Tsesses, Kobi Cohen, Florian Mangold, Anant Mantha, Bettina Frank, Guy Bartal, Frank-J. Meyer zu Heringdorf, Timothy J. Davis & Harald Giessen: Skyrmion bags of light in plasmonic moiré superlattices. Nature Physics, DOI: 10.1038/s41567-025-02873-1 .
