In a fast moving field of a 2D material, even small rotational misalignments between layers can dramatically change the behavior of the material. Scientists have previously discovered that when thin crystals of atoms are stacked with small angular mismatches, their electronic properties can change. This approach, known as Moiré engineering, has become an important strategy for designing new forms of quantum materials.
Researchers are currently natural nanotechnology Under these conditions, magnetism can also behave in surprising ways. In twisted antiferromagnetic layers, the magnetic spin pattern is not confined to small repeating Moiré unit cells. Instead, they can spread into much larger topological structures spanning hundreds of nanometers.
Huge magnetic texture that goes beyond moiré patterns
In most moiré systems, the size of the physical effect is determined directly by the interference pattern created when two crystal lattices overlap. Magnetic order in stacked van der Waals magnets was widely expected to follow this same length scale. New findings challenge that assumption.
The research team examined twisted bilayer chromium triiodide (CrI3) using scanning nitrogen-vacancy magnetometry, a technique that images magnetic fields with nanoscale precision. They observed magnetic textures reaching distances of up to about 300 nm, far exceeding the size of a single moire cell and about 10 times as large as the underlying wavelength.
Counterintuitive twist angle effect
The results revealed an unexpected pattern. As the twist angle decreases, the moiré wavelength increases. However, the magnetic texture does not simply grow with it. Instead, its size varies inversely, reaching a maximum around 1.1° and disappearing above ~2°.
This reversal shows that magnetism is not just copying the Moiré template. Rather, it results from a balance between several competing forces, such as exchange interactions, magnetic anisotropy, and Jarosinski-Moriya interactions. All of this is subtly adjusted by how the layers are rotated relative to each other. Large-scale spin dynamics simulations support this interpretation, showing the formation of extended Néel-type antiferromagnetic skyrmions spanning multiple moiré cells.
Skyrmions and low-power spintronics
These discoveries are important beyond basic physics. Skyrmions are small, stable, and topologically protected, making them promising as future information technologies. It can also be moved using very little energy. Creating them without lithography, heavy metals, or strong currents by simply adjusting the twist angle provides a clean, geometric drive path for low-power spintronic devices.
The researchers describe this phenomenon as supermoirespin ordering, highlighting that twist engineering works across multiple scales. Changes in the arrangement of atoms can generate topological structures over much larger mesoscale distances. This challenges the long-held idea that Moiré physics is only a local effect, positioning the torsion angle as a powerful thermodynamic control parameter that can tune exchange, anisotropy, and chiral interactions to stabilize topological phases.
From a practical point of view, these large and robust nail-type skyrmionic textures are suitable for integration into devices. Their large size makes them easier to detect and manipulate. At the same time, the topological protection and insulating host material demonstrate extremely low energy losses during operation. As scientists continue to study how geometry shapes quantum behavior, such new magnetic states could play an important role in the development of energy-efficient post-CMOS computing technologies.
Dr Elton Santos, Leader in Theoretical and Computational Condensed Matter Physics at the University of Edinburgh, who led the modeling aspects of the project, said: “This discovery shows that the twist is not just an electronic knob, but a magnetic knob. We see the collective spin order self-organizing on a much larger scale than a Moiré lattice. This opens the door to designing topological magnetic states just by controlling the angles, and this is a very simple handle.” have important practical consequences. ”
