Achieving uniaxial magnetic anisotropy in Ce 2 Fe 17 N 3 through Co- and Sm-substitution

Th₂Zn₁₇-type structure-based permanent magnets, such as Sm₂Fe₁₇N₃, offer strong potential as alternatives to neodymium magnets (NdFeB), but their practical use is limited by phase stability and the scarcity of Sm. Ce-based counterparts, particularly Ce₂Fe₁₇N₃, are attractive low-cost candidates, yet their intrinsic planar magnetic anisotropy restricts permanent-magnet performance. Here, we induce uniaxial magnetic anisotropy in Ce₂Fe₁₇N₃ through two approaches: (i) Co substitution on the Fe sublattice and (ii) partial substitution of Ce with Sm. Combined density functional theory and experimental results show that both strategies modify the 3d--4f interactions and band filling, yielding magnetization values up to ~1.20.28em0exT and magnetocrystalline anisotropy energies exceeding 10.28em0exMJ/m³ for Co-alloyed compositions, with significantly larger anisotropy achieved upon Sm substitution. In addition, the Sm-substituted Ce₂Fe₁₇N₃ samples exhibit enhanced high-temperature stability compared to Sm₂Fe₁₇N₃. These findings demonstrate that Ce₂Fe₁₇N₃-based alloys can deliver magnetic performance suitable for permanent-magnet applications while reducing cost and reliance on critical rare-earth elements, and they provide practical design guidelines for rare-earth-lean magnets for energy and industrial applications.