High temperature Néel skyrmions in simple ferromagnets

Article https://doi.org/10.1038/s41467-026-73775-w High temperature Néel skyrmions in simple ferromagnets Received: 21 February 2026 Accepted: 20 May 2026 Peng Wang1, Rana Saha 1,2, Holger L. Meyerheim 1, Ke Gu 1, Hakan Deniz1, David Eilmsteiner 3, Andrea Migliorini 1, Banabir Pal 1, Juan Rubio Zuazo4,5, Eugenia Sebastiani-Tofano4,5, Ilya Kostanovski 1, Abhay Kant Srivastava1, Arthur Ernst 1,3 & Stuart S. P. Parkin 1 A wide variety of chiral non-collinear spin textures have been discovered and have unique properties that make them highly interesting for technological applications. However, many of these are found in complex materials and only in a narrow window of temperature. Here, we show the formation of Néel-type skyrmions in thin layers of simple ferromagnetic alloys, namely Co-Al and CoNi-Al, over a wide range of temperature up to ~773 K, by imposing a strain gradient perpendicular to the sample plane via epitaxy with an Ir-Al underlayer. The Néel skyrmions are directly observed using Lorentz transmission electron microscopy in freestanding membranes at high temperatures and the strain gradient is directly measured from x-ray diffraction asymmetric peak profiles. Our concept allows for simple centrosymmetric ferromagnets with high magnetic ordering temperatures to exhibit skyrmions at temperatures well above room temperature, thereby, bringing closer skyrmionic electronics. 1234567890():,; 1234567890():,; Check for updates Recently, a zoology of topological chiral spin textures has been discovered in a wide range of ferro- and ferri-magnetic compounds, typically stabilized within a narrow temperature window1,2. These spin textures include Bloch3 and Néel4,5 skyrmions, perhaps the simplest of these spin textures, as well as more complex textures such as antiskyrmions6 and many more7,8. Each of these is typically nanoscopic in size, ranging from tens to hundreds of nanometers9,10, and exhibits many shapes and forms7,11. Beyond their fundamental interest, the application of skyrmions as non-volatile bits for non-volatile memory and unconventional computing devices has been proposed12–14. One of the biggest challenges to date is the stabilization of skyrmions at temperatures well above ambient temperature, especially in thin films. A prerequisite for the formation of many of the skyrmionic spin textures is the presence of a vector Dzyaloshinskii–Moriya magnetic exchange interaction (DMI)15,16 in addition to the dominant Heisenberg exchange. A DMI is possible in bulk magnetic compounds that lack crystal inversion symmetry17,18. Indeed, one avenue to search for novel skyrmionic spin textures has been to explore magnetic materials with a certain crystal symmetry that is then reflected in the form of the DMI. This led, for example, to the discovery of the anti-skyrmion in two distinct materials6,19. Another strategy is to form hetero-interfaces between thin magnetic layers and non-magnetic (or antiferromagnetic) layers that typically contain heavy atoms, which thereby gives rise to an interface-derived DMI20. These limitations considerably restrict the number of suitable magnetic materials that exhibit skyrmionic spin textures. An alternative strategy to introduce a DMI in thin films is to remove the inversion symmetry of a high symmetry material, for example, by the introduction of a strain gradient (∇tε), such as by mechanical means21, by ripples in thin film membranes22, by composition variation23, or by thin film epitaxy24–26. Perhaps the latter is the most elegant. Indeed, strain gradients normal to thin layers have been induced in several magnetic oxide thin film systems by epitaxial growth24–26, but it has been proven to be much more difficult to establish a strain gradient in metallic films27,28. Here, we show the formation of large vertical strain gradients over considerable thicknesses in metallic films formed from ferromagnetic cubic Co–Al and Co–Ni–Al alloys, which have very high Curie temperatures, by depositing them on a very special underlayer formed 1 Max Planck Institute of Microstructure Physics, Halle (Saale), Germany. 2Department of Chemistry, Indian Institute of Science Education and Research, Tirupati, India. 3Institute for Theoretical Physics, Johannes Kepler University Linz, Linz, Austria. 4Spanish CRG Beamline BM25-SpLine at the ESRF, e-mail: Grenoble, France. 5Instituto de Ciencia de Materiales de Madrid-CSIC, Madrid, Spain. Nature Communications | (2026)17:4911 1 Article from the L10 ordered alloy Ir–Al. Furthermore, we show that the vertical strain gradient in these layers gives rise to a large DMI via the direct observation of Néel-type skyrmions through Lorentz transmission electron microscopy. The skyrmions exist up to very high temperatures, as high as ~773 K, that are higher than the highest temperature at which skyrmions have previously been observed in any material. Thus, we introduce a novel strategy for creating skyrmions at very high temperatures in simple ferromagnetic layers by the introduction, via thin film epitaxy, of large strain gradients. https://doi.org/10.1038/s41467-026-73775-w Typically, thin films deposited on a substrate, via single-crystalline or polycrystalline epitaxy, maintain a constant strain (ε) up to a critical thickness at which the strain is released. We show that thin films of the tetragonal ferromagnets Co2.3Al and Co2.58Ni0.26Al rather display a significant strain gradient perpendicular to the sample plane when deposited on a suitable underlayer and within an optimal thickness range of 30 to 50 nm. To achieve large strain gradients, we explored engineered underlayers composed of the M-Al alloys (M = Ir, Pd, and Ru). These cubic alloys were chosen because at ambient temperature they grow as flat films with a highly chemically ordered L10-type crystal structure29,30 and are characterized by a larger lattice parameter than the ferromagnetic layers considered here. This lattice mismatch plays a key role in generating the strain gradient. However, of these alloys only IrAl was found to give rise to a significant strain gradient in the magnetic overlayers. The largest strain gradient (∇tε = 3.8 × 10−3/nm) was found in ferromagnetic layers of Co2.58Ni0.26Al. For strain gradients larger than approximately 7 × 10−4/nm, Néel skyrmions are observed by Lorentz Transmission Electron Microscopy (LTEM) in both Co2.3Al and Co2.58Ni0.26Al layers prepared on IrAl underlayers. Ab initio calculations establish that the largest strain gradients found experimentally give rise to substantial values of DMI that can account for the Néel skyrmions we observe both via LTEM measurements and by micromagnetic simulations. For the case of Co2.3Al, high-temperature LTEM studies using films prepared in the form of freestanding membranes show clear evidence for skyrmions up to very high temperatures of ~773 K. The strain gradients in the epitaxially grown films were determined by fitting X-ray diffraction (XRD) reflection profiles collected b (...truncated)