Researchers in Braunschweig generate magnetic field propagation with superconductors
As if triggered by a sonic boom, spin waves with record wavelengths were excited in the neighbouring magnet. Researchers from the TU Braunschweig, together with international partners, published this result in the journal Nature Nanotechnology. This pioneering achievement in physics opens up avenues for alternative, more energy-efficient electronics.
Spin waves are considered to be promising candidates for a new form of electronics. Instead of electrons, the focus here is on magnons. These quantised units of spin waves describe how spin precession propagates. Similar to electrons, magnons can transmit information in a conductor. However, they do so with much lower resistance and thus a fraction of the energy consumption.
At TU Braunschweig, the Cryogenic Quantum Electronics working group, together with international partners, has now set a new record for the wavelength of excited propagating magnons. The researchers led by Professor Oleksandr Dobrovolskiy used another quasiparticle, fluxons, to excite the spin waves. “Fluxons move as magnetic flux quanta of a superconductor at speeds of up to 10 kilometres per second. We succeeded in using the ultra-fast fluxons to excite a spin wave in a neighbouring magnet,‘ explains Dobrovolskiy. ’This effect can be imagined as similar to the bow wave created by a speedboat in water. Except that our boat is so fast that it literally creates a kind of sonic boom.”
The team also observed a characteristic feature of this interaction: a so-called Shapiro step in the electrical response of the superconductor. This effect shows that the motion of the fluxons is synchronised with the generated spin waves – an indication of coherent coupling between the two systems.
New possibilities for future information systems
Beyond fundamental physics, this discovery opens up new possibilities for spin wave-based electronics. ‘Our results could pave the way for smaller, faster and more efficient components for future information processing systems,’ says Professor Dobrovolskiy.
With the recently approved continuation of funding for the QuantumFrontiers cluster of excellence until 2032 and the establishment of modern laboratory facilities at the Laboratory for Emerging Nanometrology (LENA) at TU Braunschweig, the group on Cryogenic Quantum Electronics is now ideally positioned to scale hybrid fluxon-magnon systems to atomic dimensions and conduct experiments with individual quantum excitations.
As part of the publication in Nature Nanotechnology, the researchers also collaborated with partners from Huazhong University of Science and Technology in China, Goethe University Frankfurt am Main, the University of Vienna and the University of Bordeaux.
Prof. Dr. Oleksandr Dobrovolskiy
Technische Universität Braunschweig
Electrical Measurement Science and Fundamental Electrical Engineering
Abteilung der Kryogenen Quantenelektronik
Hans-Sommer-Str. 66
38106 Braunschweig
Germany
Mail: oleksandr.dobrovolskiy@tu-braunschweig.de
Dobrovolskiy, O.V., Wang, Q., Vodolazov, D.Y., Sachser, R., Huth, M., Knauer, S., Buzdin, A. I. Moving Abrikosov vortex lattices generate sub-40-nm magnons. Nat. Nanotechnol. (2025). https://doi.org/10.1038/s41565-025-02024-w <https://doi.org/10.1038/s41565-025-02024-w
https://magazin.tu-braunschweig.de/en/pi-post/record-spin-waves-thanks-to-flux-q...
Fluxon-Lagnon-Interaction
Copyright: CryoQuant/TU Braunschweig
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