Researchers have shown a new type of magnetism in very thin layers of material for the first time. This finding matters for future tech that stores more data in smaller spaces and helps explain magnetic forces in flat systems. The work, led by University of Stuttgart with partners from other countries, is published in Nature Nanotechnology.
The new magnetic state happens in four thin layers of chromium iodide, a chemical compound. Researchers can control this magnetism by adjusting how electrons interact between layers. The magnetism stays strong even when outside conditions change.
Two-dimensional materials are super-thin structures, just a few atoms thick, arranged in a crystal lattice. These materials act differently from thicker, three-dimensional versions.
To make the new state, researchers twisted two double layers of chromium iodide slightly against each other. This twist creates skyrmions, which are tiny, stable swirls of magnetism at the nanoscale - one billionth of a meter. Skyrmions could carry information in magnets very reliably. This is the first time skyrmions were made and seen in a twisted flat magnetic material. Without the twist, the layers show no outer magnetic field.
How the researchers detected the magnetism
Spotting this weak magnetism was hard, so the researchers used a special microscope with quantum sensing, which relies on nitrogen-vacancy centers in diamonds - flaws where a nitrogen atom replaces carbon next to an empty spot. These centers, improved over 20 years, detect faint signals.
The results mean current theories about electron groups in thin magnets need updates. Modeling and computer simulations came from other researchers. This could lead to denser data storage, like in hard drives, and better grasp of flat magnet behaviors. While more work is needed, it opens doors to advanced tech.
"Our results are therefore of direct relevance for next-generation data storage technologies," said research leader Jörg Wrachtrup. "At the same time, they are of fundamental importance as they provide new insights into magnetic interactions in atomically thin materials.“