Tiny Magnets, Big Potential: How Spin Waves Let Particles “Talk” in 2D Materials

Physicists have discovered that electronic excitations in 2D magnets can interact through spin waves – ripples in a material’s magnetic structure.

This breakthrough allows excitons (electron-hole pairs) to influence one another indirectly, like objects disturbing water. The interaction, demonstrated in a magnetic semiconductor called CrSBr, can be toggled on and off with magnetic fields, opening doors to revolutionary technologies like optical modulators, logic gates, and especially quantum transducers for future quantum computers and communication systems.

Discovery Unlocks Spin-Wave Mediated Interactions

Physicists at The City College of New York have made a significant breakthrough in understanding how electronic excitations can interact through spin waves. The discovery, made by the Laboratory for Nano and Micro Photonics (LaNMP) team led by physicist Vinod Menon, could pave the way for next-generation technologies—including optical modulators, all-optical logic gates, and quantum transducers. The research was recently published in Nature Materials.

The team demonstrated that excitons – pairs of electrons and the “holes” they leave behind – can influence each other indirectly through spin waves, or magnons, in atomically thin (2D) magnetic materials. These magnons act like ripples in the material’s magnetic structure, allowing excitons to interact even without direct contact.

Magnons: The Hidden Connectors

“Think of magnons as tiny flip-flops of atomic magnets inside the crystal. One exciton changes the local magnetism, and that change then influences another exciton nearby. It’s like two floating objects pulling toward each other by disturbing water waves around them,” said Menon.

To demonstrate this effect, the researchers used a 2D magnetic semiconductor called CrSBr, which they had previously shown to exhibit strong interactions between light and matter (Nature, 2023).

Post-doctoral fellows Biswajit Datta and Pratap Chandra Adak led the research along with graduate students Sichao Yu and Agneya Dharmapalan in collaboration with the groups at the CUNY Advanced Science Research Center, University of Chemistry and Technology – Prague, RPTU – Kaiserslautern, Germany and NREL, USA.

Magnetic Control Opens New Possibilities

“What is especially exciting about this discovery is that the interaction between excitons can be controlled externally using a magnetic field, thanks to the tunable magnetism of 2D materials. That means we can effectively switch the interaction on or off, which is hard to do with other types of interactions,” said Datta.

Towards Quantum Signal Conversion

“One particularly exciting application enabled by this discovery is in the development of quantum transducers – devices that convert quantum signals from one frequency to another, such as from microwave to optical. These are key components for building quantum computers and enabling the quantum internet,” said Adak, another lead author of this work.

Reference: “Magnon-mediated exciton–exciton interaction in a van der Waals antiferromagnet” by Biswajit Datta, Pratap Chandra Adak, Sichao Yu, Agneya Valiyaparambil Dharmapalan, Siedah J. Hall, Anton Vakulenko, Filipp Komissarenko, Egor Kurganov, Jiamin Quan, Wei Wang, Kseniia Mosina, Zdeněk Sofer, Dimitar Pashov, Mark van Schilfgaarde, Swagata Acharya, Akashdeep Kamra, Matthew Y. Sfeir, Andrea Alù, Alexander B. Khanikaev and Vinod M. Menon, 21 March 2025, Nature Materials.
DOI: 10.1038/s41563-025-02183-0

The work at CCNY was supported by the U.S. Department of Energy – Office of Basic Energy Sciences, The Army Research Office, The National Science Foundation, and The Gordon and Betty Moore Foundation.

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