The key to ultra-dense next-generation data storage may lie in a newly discovered magnetic state within twisted 2D materials—German scientists uncover a 'super-moiré' magnetic breakthrough

A group of scientists led by The University of Stuttgart has detected anomalous magnetic behavior in twisted, two-dimensional chromium triiodide, uncovering extended spin patterns that reach beyond the material’s intrinsic Moiré pattern. The results, published in the journal Nature Nanotechnology on February 2, were detected in twisted double-bilayer chromium triiodide systems via nanoscale magnetic imaging at cryogenic temperatures. The study might significantly impact the development of ultra-dense magnetic data storage.

Twisted van der Waals materials have emerged as a key area of investigation for scientists in recent years, as minor angular misalignments between atomically thin layers generate moiré superlattices that Significantly alter electronic and magnetic properties.

Using scanning nitrogen-vacancy magnetometry, the researchers captured direct images of ordered, dot-shaped magnetic patterns extending across several moiré unit cells. As the twist angle increased within a narrow long-angle range, the characteristic size of these textures expanded, reaching approximately 300 nanometers near a 1.1-degree twist before disappearing at around two degrees. Individual features in those textures are on the order of about 60 nanometers.

Unlike earlier reports of moiré-locked magnetic states in chromium triiodide, the researchers note that these textures extend beyond a single stacking arrangement or local energy minimum in the moiré lattice. Instead, they give rise to a higher-order “super-moiré” magnetic state that rearranges magnetism across a larger length scale.

The researchers link this behavior to the interplay among exchange interactions, magnetic anisotropy, and interfacial Dzyaloshinskii-Moriya interaction — an antisymmetric exchange interaction originating from Spin-orbit coupling—which gains importance in twisted bilayer interfaces. Once the moiré period is reduced enough, these competing energies promote magnetic ordering that separates from the geometric moiré pattern, generating textures that extend across several cells.

Antiferromagnetic skyrmions attract significant attention from researchers due to their potential to mitigate the skyrmion Hall effect, a trait that could streamline motion control in upcoming spintronic designs by Enabling smoother and more precise movement compared to their ferromagnetic equivalents. In this study, the researchers demonstrate that the twist angle can serve as a powerful tuning parameter to stabilize these magnetic states in atomically thin materials, reconfiguring magnetic order without altering the composition Number of layers.

As with all studies like this, it’s crucial to keep in mind that the research is still in its earliest phases. Measurements were carried out at low temperatures, and chromium triiodide is air-sensitive, making it unsuitable for direct use in any applications beyond the laboratory. However, the authors observe that the fundamental mechanism can be applied to other layered magnetic materials, including those with higher ordering temperatures.

This research may also hold significance for next-generation magnetic data storage technologies and deeper insights into magnetic interactions within two-dimensional systems. “As data volumes continue to grow, future magnetic storage media must be able to store information reliably at ever higher densities,” said Professor Jörg Wrachtrup, Head of the Center for Applied Quantum Technologies at the University Of Stuttgart, in comments to Interesting Engineering. “Our results are therefore directly relevant for next-generation data storage technologies.”

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