Direct observation of nanoscale pinning centers in Ce(Co0.8Cu0.2)5.4 permanent magnets
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| Main Authors: | , , , , , , , , , , , , , , , , , |
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| Format: | Preprint |
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2025
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| _version_ | 1866914042455523328 |
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| author | Polin, Nikita Shen, Shangbin Maccari, Fernando Aubert, Alex Adabifiroozjaei, Esmaeil Smoliarova, Tatiana Yang, Yangyiwei Chen, Xinren Skourski, Yurii Saxena, Alaukik Kovács, András Dunin-Borkowski, Rafal E. Farle, Michael Xu, Bai-Xiang Molina-Luna, Leopoldo Gutfleisch, Oliver Gault, Baptiste Skokov, Konstantin |
| author_facet | Polin, Nikita Shen, Shangbin Maccari, Fernando Aubert, Alex Adabifiroozjaei, Esmaeil Smoliarova, Tatiana Yang, Yangyiwei Chen, Xinren Skourski, Yurii Saxena, Alaukik Kovács, András Dunin-Borkowski, Rafal E. Farle, Michael Xu, Bai-Xiang Molina-Luna, Leopoldo Gutfleisch, Oliver Gault, Baptiste Skokov, Konstantin |
| contents | Permanent magnets containing rare earth elements are essential components for the electrification of society. Ce(Co1-xCux)5 permanent magnets are a model system known for their substantial coercivity, yet the underlying mechanism remains unclear. Here, we investigate Ce(Co0.8Cu0.2)5.4 magnets with a coercivity of ~1 T. Using transmission electron microscopy (TEM) and atom probe tomography (APT), we identify a nanoscale cellular structure formed by spinodal decomposition. Cu-poor cylindrical cells (~5-10 nm in diameter, ~20 nm long) have a disordered CeCo5-type structure and a composition Ce(Co0.9Cu0.1)5.3. Cu-rich cell boundaries are ~ 5 nm thick and exhibit a modified CeCo5 structure, with Cu ordered on the Co sites and a composition Ce(Co0.7Cu0.3)5.0. Micromagnetic simulations demonstrate that the intrinsic Cu concentration gradients up to 12 at.% Cu/nm lead to a spatial variation in magnetocrystalline anisotropy and domain wall energy, resulting in effective pinning and high coercivity. Compared to Sm2Co17-type magnets, Ce(Co0.8Cu0.2)5.4 displays a finer-scale variation of conventional pinning with lower structural and chemical contrast in its underlying nanostructure. The identification of nanoscale chemical segregation in nearly single-phase Ce(Co0.8Cu0.2)5.4 magnets provides a microstructural basis for the long-standing phenomenon of "giant intrinsic magnetic hardness" in systems such as SmCo5-xMx, highlighting avenues for designing rare-earth-lean permanent magnets via controlled nanoscale segregation. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2509_13859 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Direct observation of nanoscale pinning centers in Ce(Co0.8Cu0.2)5.4 permanent magnets Polin, Nikita Shen, Shangbin Maccari, Fernando Aubert, Alex Adabifiroozjaei, Esmaeil Smoliarova, Tatiana Yang, Yangyiwei Chen, Xinren Skourski, Yurii Saxena, Alaukik Kovács, András Dunin-Borkowski, Rafal E. Farle, Michael Xu, Bai-Xiang Molina-Luna, Leopoldo Gutfleisch, Oliver Gault, Baptiste Skokov, Konstantin Materials Science Permanent magnets containing rare earth elements are essential components for the electrification of society. Ce(Co1-xCux)5 permanent magnets are a model system known for their substantial coercivity, yet the underlying mechanism remains unclear. Here, we investigate Ce(Co0.8Cu0.2)5.4 magnets with a coercivity of ~1 T. Using transmission electron microscopy (TEM) and atom probe tomography (APT), we identify a nanoscale cellular structure formed by spinodal decomposition. Cu-poor cylindrical cells (~5-10 nm in diameter, ~20 nm long) have a disordered CeCo5-type structure and a composition Ce(Co0.9Cu0.1)5.3. Cu-rich cell boundaries are ~ 5 nm thick and exhibit a modified CeCo5 structure, with Cu ordered on the Co sites and a composition Ce(Co0.7Cu0.3)5.0. Micromagnetic simulations demonstrate that the intrinsic Cu concentration gradients up to 12 at.% Cu/nm lead to a spatial variation in magnetocrystalline anisotropy and domain wall energy, resulting in effective pinning and high coercivity. Compared to Sm2Co17-type magnets, Ce(Co0.8Cu0.2)5.4 displays a finer-scale variation of conventional pinning with lower structural and chemical contrast in its underlying nanostructure. The identification of nanoscale chemical segregation in nearly single-phase Ce(Co0.8Cu0.2)5.4 magnets provides a microstructural basis for the long-standing phenomenon of "giant intrinsic magnetic hardness" in systems such as SmCo5-xMx, highlighting avenues for designing rare-earth-lean permanent magnets via controlled nanoscale segregation. |
| title | Direct observation of nanoscale pinning centers in Ce(Co0.8Cu0.2)5.4 permanent magnets |
| topic | Materials Science |
| url | https://arxiv.org/abs/2509.13859 |