In our latest study, we examined Sm2(Co,Fe,Cu,Zr)17 high-performance magnet with perfect thermal and chemical stability. These industry-grade magnets are used in advanced electric motors, and contain a higher amount of iron to boost motor efficiency, however, to further improve the properties of this magnetic material, it is indispensable to understand the fundamental reasons behind their outstanding magnetic properties. In this manuscript, we set out to find which parts of their internal structure help them stay strong, and which parts might limit them, because even small changes in how atoms are arranged, or how chemical elements are distributed, can significantly change the magnet’s overall strength and stability.

By using a suite of advanced imaging techniques, including microscopes capable of viewing individual atoms, we showed that even though miscrostructure of magnets with high and modest performance look structurally similar, their chemical makeup is very different. Magnets perform best when key elements are distributed in an optimal way, and this balance shifts significantly between high-strength and low-strength magnetic zones inside the material.

One of our most important findings was that the best-performing magnets contain a special combination of ultra-small internal components, including an extremely thin copper layer – just one to two atoms thick – at the edge of a key structural phase inside the material. This tiny layer acts like a pinning barrier, helping the magnet resist demagnetization. This means electric motors and generators built with these magnets can run reliably in far harsher conditions than before.

Our study also challenges a common assumption in magnet research. Grain boundaries (the internal lines between crystal grains of 50-100 micrometers in size) were long believed to be a “weak link” – the area where demagnetization processes begin. Contrary to that, we found they do not significantly reduce the overall strength of the magnet. Instead, the real opportunity for improvement lies inside the grains themselves: magnets become stronger and more stable when their internal nanostructure is carefully optimized at the atomic level.

This work is the result of very close scientific cooperation between various institutes and industry, namely: Institute of Materials Science, Technische Universität Darmstadt; Max Planck Institute for Sustainable Materials, Düsseldorf; Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich; School of Physics and Astronomy, University of Glasgow; VACUUMSCHMELZE GmbH & Co. KG, Hanau; Faculty of Physics and Center for Nanointegration (CENIDE), Universität Duisburg-Essen, Duisburg. The published manuscript is also a summary of pilot project in the framework of Collaborative Research Centre/Transregio (CRC/TRR) 270.

S. Giron, N. Polin, E. Adabifiroozjaei, Y. Yang,A. Kovács, T. P. Almeida, D. Ohmer, K. Üstüner, A. Saxena, M. Katter, F. Maccari, I. A. Radulov, C. Freysoldt, R. E. Dunin-Borkowski, M. Farle, K. Durst, H. Zhang, L. Alff, K. Ollefs, B.-X. Xu, O. Gutfleisch, L. Molina-Luna, B. Gault, K. P. Skokov
Identifying grain boundary and intragranular pinning centres in Sm2(Co,Fe,Cu,Zr)17 permanent magnets to guide performance optimisation
Nat Commun 16, 11335 (2025).
DOI: 10.1038/s41467-025-67773-7