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The properties of ultrathin magnets can be specifically altered by a slight twist between two atomic monolayers. This is the conclusion reached by an international research team led by TU Darmstadt in a study published in Nature Communications. The findings open new prospects for future memory devices.
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For the first time, the researchers observed that an extremely thin magnetic material—a so-called two-dimensional van der Waals magnet—"stores" its magnetic state: It responds to a magnetic field and retains some of its magnetization even when the applied field changes. This "memory" is known as hysteresis and forms the basis of many data storage systems.
A twist changes the magnet
The material studied, chromium sulfide bromide (CrSBr), consists of individual layers that can be stacked and are each magnetic. Adjacent layers are magnetized in exactly opposite directions, so their magnetic fields cancel each other out externally as a so-called antiferromagnet.
The researchers stacked two such layers on top of one another and twisted them by about 3 degrees relative to each other. This creates a fine structural pattern (moiré pattern) that alters how the two layers interact magnetically.
Using a light-based measurement technique at very low temperatures, the research team observed how the material reacts to an external magnetic field. Unlike untwisted bilayers, the twisted structure exhibited hysteresis particularly clearly. In addition, the researchers developed a theoretical model that accurately describes the observed magnetic switching processes.
This revealed that, during switching, the twisted bilayer reacts largely like a single uniform magnet—even though its magnetic properties are not exactly the same throughout the sample. Overall, the results demonstrate that the magnetic properties of such thin materials can be tailored solely through targeted twisting, known as "twist engineering."
From basic physics to devices
This approach has already yielded promising results. For example, superconductivity—the flow of current with no resistance—was discovered in such twisted, extremely thin materials. So-called Mott insulators have also been demonstrated. These materials block the flow of current even though, according to classical theory, they should conduct it.
The study combines basic research with potential practical applications. In the long term, such materials could form the basis for novel data storage devices or electronic components that can be flexibly reprogrammed. So-called spintronic devices are also conceivable—a new type of electronics that processes and stores information in a particularly energy-efficient manner.
In addition to the Institute of Condensed Matter Physics at TU Darmstadt and the Rhineland-Palatinate Technical University of Kaiserslautern-Landau, the University of Chemistry and Technology in Prague and the National Institute for Materials Science in Tsukuba, Japan, were also involved in the research.
The fabrication and characterization of the CrSBr samples and the magneto-optical measurements were carried out at TU Darmstadt by Priyanka Mondal, Wenze Lan and Lennard Hopf from Professor Bernhard Urbaszek's Hybrid Quantum Systems research group. The theoretical modeling was carried out in close collaboration.
More information: Priyanka Mondal et al, Twist-tuned exchange and hysteresis in a bilayer van der Waals magnet, Nature Communications (2026). DOI: 10.1038/s41467-026-75186-3
Provided by Technische Universitat Darmstadt
This story was originally published on Phys.org.
