Twisting Atoms to Build Magnets
Researchers at the University of Edinburgh have discovered that a slight rotational misalignment between atomically thin magnetic layers can generate remarkably large magnetic structures called skyrmions — topological features that could form the basis of next-generation computing devices requiring only a fraction of the energy consumed by current electronics.
The discovery, published in Nature Nanotechnology, demonstrates that twisting two layers of chromium triiodide — a magnetic material just atoms thick — produces skyrmion-like patterns stretching up to 300 nanometers. That size far exceeds what the underlying twist pattern would predict, revealing that the relationship between geometric manipulation and magnetic behavior is more complex and more useful than previously understood.
What Are Skyrmions?
Magnetic skyrmions are swirling patterns in the magnetic orientation of atoms within a material. Imagine a field of compass needles all pointing north, with a single region where the needles spiral through every direction before returning to north at the boundary. That spiraling region is a skyrmion — a stable, self-contained magnetic structure that resists being unwound.
This stability makes skyrmions extraordinarily attractive for information storage and processing. A skyrmion can represent a bit of data — its presence encoding a one, its absence a zero — but unlike the magnetic domains used in conventional hard drives, skyrmions can be created, moved, and destroyed with minimal energy. Theoretical calculations suggest skyrmion-based devices could operate at a fraction of the power consumption of current magnetic storage, addressing one of the fundamental challenges in computing's escalating energy demands.
The challenge has been creating skyrmions reliably and at useful scales. Previous methods required external magnetic fields, specific temperature conditions, or complex material engineering — all of which limited practical applications. The Edinburgh team's twist-based approach offers a fundamentally simpler pathway.
The Unexpected Scale
When researchers stack two sheets of atomically thin material at a slight angle, they create a moire pattern — the same visual effect seen when two mesh screens overlap at an angle. In twisted bilayer materials, this moire pattern creates a periodic variation in the electronic and magnetic environment that can be tuned by adjusting the twist angle.
The surprise in the Edinburgh experiments was that the magnetic skyrmions did not simply mirror the moire pattern. Instead, they grew far larger — reaching hundreds of nanometers compared to the much smaller moire wavelength. Even more unexpectedly, the skyrmion size did not increase continuously as the twist angle decreased. Instead, it peaked at a specific angle of approximately 1.1 degrees and diminished above 2 degrees.
This behavior indicates that the magnetism is not simply copying the geometric template imposed by the twist. Instead, it emerges from a competition between multiple physical forces — exchange interactions between neighboring magnetic atoms, magnetic anisotropy that favors certain orientations, and Dzyaloshinskii-Moriya interactions that promote spiraling magnetic textures. The twist angle tunes the balance between these competing forces, and at the sweet spot of 1.1 degrees, conditions favor the formation of large, stable skyrmions.
Geometry as an Engineering Tool
Dr. Elton Santos, who led the research, emphasized that the findings demonstrate twisting is not just an electronic knob — a reference to the extensive research on twisted graphene — but a magnetic one as well. The ability to create and control magnetic structures through geometry alone, without lithography, external fields, or electrical currents, represents a fundamentally cleaner approach to engineering magnetic devices.
Conventional methods for creating nanoscale magnetic structures rely on top-down fabrication techniques — etching patterns into materials using electron beams or photolithography. These processes are expensive, limited in resolution, and introduce defects. A twist-based approach bypasses these limitations entirely, using the natural properties of the material itself to generate the desired magnetic configurations.
The Road to Spintronic Devices
Spintronics — the field of electronics that exploits the magnetic spin of electrons rather than just their electrical charge — has long promised devices that are faster, smaller, and more energy-efficient than conventional electronics. Skyrmions are considered one of the most promising building blocks for practical spintronic devices because they combine small size, stability, and low-energy manipulation.
The Edinburgh discovery advances this vision by demonstrating a fabrication method compatible with the two-dimensional materials that are already the focus of intense research in both academia and industry. Chromium triiodide is part of a growing family of 2D magnetic materials that can be produced by mechanical exfoliation — the same scotch tape method that first isolated graphene — or by chemical vapor deposition at wafer scale.
If twist-controlled skyrmions can be produced in these materials reliably, the path to prototype devices shortens considerably. The magnetic structures are already at a scale relevant to data storage — 300 nanometers is large enough to be read and written by existing scanning probe techniques, while small enough to enable high-density storage if the structures can be further miniaturized through material and twist optimization.
Fundamental Questions Remain
The research opens as many questions as it answers. The dynamics of skyrmion formation during the twisting process are not fully understood. The temperature stability of twist-generated skyrmions — critical for any practical application — requires further investigation. And while chromium triiodide demonstrated the principle, other 2D magnetic materials may prove more suitable for device applications.
What the Edinburgh team has established is a new and powerful design principle: that geometry can control magnetism at the nanoscale in ways that were not previously anticipated. In a field where progress often comes from discovering new materials or new fabrication methods, the demonstration that a simple twist can generate complex and useful magnetic structures represents a conceptual breakthrough as much as a technical one.
This article is based on reporting by Science Daily. Read the original article.
