Magnetic skyrmions, tiny swirling structures of magnetization, have drawn attention as candidates for ultra-dense, energy-efficient memory. But most materials that host them work only at low temperatures or within a narrow window. Centrosymmetric magnets with easy-axis anisotropy, such as Fe3Sn2, offered a route to widening that window, yet combining a high Curie temperature, broad skyrmion stability and tunable anisotropy in one material remained rare. Fe3Ge with its kagome lattice stands out among its archive neighbors: whereas in Fe3Sn2 skyrmions are stable over a wide range, here they additionally coexist with Dirac fermions and a large anomalous Hall effect. The work bridges the gap between real-space and momentum-space topology in a single material.
Fe3Ge single crystals were grown by the tin-flux method. Composition was confirmed by energy-dispersive X-ray spectroscopy, and structure by Laue diffraction and high-resolution transmission electron microscopy. Magnetic properties were measured on a SQUID magnetometer, and transport with the standard four-probe method in a cryogenic system. Spin textures were imaged using Lorentz transmission electron microscopy on a lamella about 100 nm thick cut by a focused ion beam. The electronic structure was calculated with the linearized augmented plane wave method in the WIEN2k package, and the anomalous Hall conductivity with a tight-binding model based on Wannier functions. The demagnetization factor was taken into account from the sample geometry.
At 300 K, the anomalous Hall conductivity of Fe3Ge reaches 380 Ω⁻¹cm⁻¹, comparable to the best topological kagome materials. Magnetic measurements revealed a spin-reorientation transition at 375 K: below this temperature the easy axis lies in the plane, above it, perpendicular to the plane. The anisotropy constant changes sign from −4.1×10⁵ J/m³ at 2 K to +0.36×10⁵ J/m³ at 400 K. Lorentz microscopy showed that in the easy-axis phase, at fields from 727 to 1200 mT, Bloch skyrmions about 250 nm in diameter form with equal populations of the two helicities, indicating a dipolar stabilization mechanism. The skyrmions persist across the entire range from 375 to 650 K, one of the widest windows among known materials. At 650 K the domain contrast disappears, confirming the Curie temperature.
The work demonstrates that the Dirac kagome magnet Fe3Ge unites real-space topology (skyrmions) and momentum-space topology (a large anomalous Hall effect). Unlike neighboring studies, where skyrmions were examined in materials without pronounced band topology or with a narrow stability window, here both phenomena coexist in a single crystal at temperatures up to 650 K. This opens a path to devices in which spin textures can be controlled by electric fields through topological electronic states. The result also explains the previously observed enhancement of the topological Hall effect and the topological Nernst effect below 375 K: there the contribution comes from microscopic noncoplanar spin structures, and above it, from mesoscopic skyrmions.
The immediate next step is to lower the spin-reorientation temperature by chemical substitution, so that skyrmions appear at room temperature. Previous work has shown that substituting some of the iron or germanium atoms shifts the transition below 300 K. Another direction is optimizing sample thickness and geometry: dipolar skyrmions are sensitive to confinement, and fine-tuning will allow their size, density and nucleation to be controlled. Also promising is studying how skyrmions interact with Dirac fermions in transport experiments on thin films, where the skyrmion contribution to the topological Hall effect may become measurable.
The results matter for spintronics, which needs skyrmions stable at high temperatures for memory and logic. The material is also of interest for caloritronics thanks to its large anomalous Nernst effect, and for research on topological phases in frustrated magnets.
Carry out systematic substitution in Fe3Ge to lower the spin-reorientation temperature and test skyrmion stability at room temperature. Fabricate thin films with controlled thickness and study the skyrmion contribution to transport properties.
In the physics of magnetic skyrmions, the question of what stabilizes them in centrosymmetric systems without Dzyaloshinskii-Moriya interaction remains open. The work shows that dipolar interactions and competing anisotropy are enough for a wide stability window. Another unsolved problem is the link between real-space and momentum-space topology in a single material, and Fe3Ge offers a rare chance to probe it experimentally.
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What the work does
The work presents Fe3Ge, a Dirac kagome magnet in which skyrmions remain stable from 375 to 650 K. The authors grew single crystals, measured magnetic and transport properties, imaged the skyrmions with Lorentz TEM, and tied their appearance to a spin-reorientation transition and a dipolar mechanism.
Where its strength is
The combination of a wide temperature window of skyrmion stability, a high Curie temperature, and topological electronic bands makes Fe3Ge a unique platform for studying the interplay between topology in real space and momentum space.
Where it could go next
Worth trying
Why this may matter
If high-temperature skyrmion stability can be paired with control by currents or waves, Fe3Ge could become the basis for practical spintronic devices that operate at room temperature and above.
Nearby works in our archive
The archive is sparse around this work: the closest review is only 0.56, against a usual 0.64. It looks like few have drilled nearby.
Skyrmions are named after the British physicist Tony Skyrme, who proposed them in 1962 as a model for describing nuclear particles. Today these "particles" live in magnetic crystals and can be smaller than one hundred nanometers.
In Arthur C. Clarke's novel The City and the Stars, information is stored in crystal lattices that rearrange almost without energy cost. Magnetic skyrmions in Fe3Ge are a real step toward such memory: they are tiny, robust and move under ultralow currents.