Excitons are being discussed as light storage devices in materials science and information technology. The luminous quasiparticles move through individual layers of quantum materials and can absorb and emit light highly efficiently. They are created when the light pulse from a laser excites an electron, leaving behind a positively charged “hole”. Electron and hole attract each other and together behave like a new, independent particle. The moment the quasiparticle decays again, it glows and can be measured in high-tech laboratories.
Excitons in ultra-thin quantum materials have been the subject of intensive research for more than ten years, including by Alexey Chernikov and his team. In the Cluster of Excellence ctd.qmat – Complexity, Topology and Dynamics in Quantum Materials at the Universities of Würzburg and Dresden, Chernikov and an international research team at the Dresden site have now made a surprising discovery: excitons can be carried along by the magnetic excitations of a quantum material and thus even be accelerated ultrafast:
“The fact that the motion of optical particles can be influenced magnetically is new. Until now, we only knew that the transport of electrons could be controlled by the magnetic order in a quantum material. This is how some sensors in smartphones work, for example. The newly discovered combination of optics and magnetism can open up completely new technological possibilities,” explains Florian Dirnberger, head of an Emmy Noether junior research group at the Technical University of Munich and previously responsible for carrying out the research project as a postdoc at Alexey Chernikov’s Chair of Ultrafast Microscopy and Photonics.
Spin waves enable ultrafast transport
The antiferromagnetic semiconductor chromium sulphur bromide (CrSBr) becomes magnetic at -141.15 degrees Celsius. The electrons inside the material then start to wobble and try to align themselves in parallel. The material under investigation consists of two independent, ultra-thin layers. The common alignment of the magnetic moments – known as spins – varies from one material layer to the next. “When we excite the cooled material with a laser pulse, the electron spins start to oscillate and move outwards in waves – as if you were throwing a stone into a lake,” explains Sophia Terres, Alexey Chernikov’s doctoral student and co-responsible for the experiments.
When the research team examined the quantum material using highly sensitive spectroscopy in the high-tech laboratory, they made a remarkable discovery: the excitons did not move through the material randomly – as is usually the case – but were carried by the spin waves: “The luminous quasiparticles surf on the spin waves, which actually accelerates them extremely. We have never measured such a fast exciton movement,” says Terres.
After it was only discovered about five years ago that excitons can be created in the antiferromagnetic semiconductor CrSBr, the present work has demonstrated an additional, completely new phenomenon: The transport of excitons depends on the magnetic order of the semiconductor. This correlation was discovered by the ctd.qmat research team for the first time in a quantum material.
Magneto-optics becomes possible
The experimental proof provided by Chernikov and his team could make magneto-optical quantum technologies possible in the future. Until now, electromagnetic applications have been standard in industry, electronics, communication and mobility. If optical excitations – such as excitons – can be controlled magnetically, this could be interesting for hybrid technologies: “Circuits based on light are faster and transport information with less loss than current technologies,” explains Dirnberger. “Now we know that optical components could be controlled magnetically – this is an exciting new perspective for future technologies and could give spintronics a big boost in the coming years.”
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© Kilian Neddermeyer
Caption: Quasiparticles surfing on magnetic waves: When a laser pulse hits a layer of material, excitons are created, which then move through the layer as an electron-hole pair. Their movement is controlled and accelerated by the magnetic alignment of the spins (triangular peaks) in the material layers, which is wave-shaped.
Publication
Exciton transport driven by spin excitations in an antiferromagnet; Florian Dirnberger, Sophia Terres, Zakhar A. Iakovlev, Kseniia Mosina, Zdenek Sofer, Akashdeep Kamra, Mikhail M. Glazov & Alexey Chernikov; Nature Nanotechnology 21, 65-70 (2026), https://doi.org/10.1038/s41565-025-02068-y.
ctd.qmat
The Cluster of Excellence ctd.qmat – Complexity, Topology and Dynamics in Quantum Matter at Julius-Maximilians-Universität Würzburg and Technische Universität Dresden researches and develops novel quantum materials with customized properties. Around 300 scientists from more than 30 countries are designing the foundations for the technologies of the future at the interface of physics, chemistry and materials science. In 2026, the cluster entered the second funding period of the Excellence Strategy of the German federal and state governments – with an expanded focus on the dynamics of quantum processes.
Contact
Prof. Alexey Chernikov
Institute of Applied Physics
Technical University of Dresden
Email: alexey.chernikov@tu-dresden.de
Tel: +49 351 463 336439
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Further links
👉 https://tu-dresden.de
Photo: Kilian Neddermeyer
