Enhanced structural stability and magnetism of SmCo₃ permanent magnet doped with 3d transition metals: an ab initio study

Alloying with transition metal elements akin to Sm(CoFeCuZr)_z can effectively enhance the magnetic properties of SmCo-based permanent magnets. However, the effects of transition metals doping on its magnetic properties, detailed atomic occupancy and the mechanism for structural stability remain unclear. Specifically, for SmCo₃ magnets, there is minimal theoretical study available. Herein, based on first-principles calculations, we systematically investigated the influence of 3d transition metals (TMs) doping on the structural stability, magnetic properties and electronic characteristics of SmCo₃ magnets. Our results show that Sc, Ti, V, Fe, Ni, Cu and Zn preferentially occupy the 18h lattice site, while Cr and Mn occupy the 3b and 6c lattice sites, respectively. Doping with Ti, Cr, Mn, Fe, Ni, Cu and Zn contributes to enhancing the stability of SmCo₃, whereas the doping of Sc and V adversely affects structural stability. The magnetic calculations reveal that Cr, Mn and Fe doping significantly enhances the total magnetic moment. It is also found that lower concentrations of Cr doping can significantly enhance the magnetocrystalline anisotropy energy (MAE). More intriguingly, when the doping concentrations of Sc, Ni and Cu reach 14.81 at%, 22.22 at% and 22.22 at%, respectively, the magnetic easy axis of the system shifts from out-of-plane to in-plane. The optimal doping concentration of Fe in the SmCo₃ system is determined to be 37.04 at%. The Curie temperature of pure SmCo₃ is 483.9 K. Our theoretical study offers valuable theoretical guidance for experimental exploration toward SmCo-based permanent magnets with higher performance.