Binary and ternary metallic compounds with soft magnetic properties: predictions from density functional theory calculations

Nanocrystalline magnetic materials have fundamental and technological importance, due to their soft magnetic properties. These materials have a two-phase microstructure, a nanocrystalline ferromagnetic phase with D0₃ structure and a residual amorphous alloy phase. FINEMET (Fe_73.5Si_13.5Nb₃B₉Cu_1, with the nanocrystalline phase Fe₃Si) is one such material, having large saturation magnetization, low magnetocrystalline anisotropy, and coercivity. Still, it has some disadvantages related to its brittleness and power dissipation. With the aim of finding better soft magnetic alloys, we performed a systematic computational search across binary (D0₃, formula X₃Z) and ternary (L₂₁, XY₂Z) compounds, using generalized gradient approximation calculations. We choose the 3d-transition metals (Sc, Ti, V, Cr, Mn, Fe, Co and Ni) as X or Y element, and Al, Si, P, Ga, Ge, As, In, Sn and Sb as Z, for a total of 576 alloy combinations. We have filtered the best candidates based on their magnetization, crystalline anisotropy, heat of formation, and ductility. We have thus found 12 compounds (including, e.g., Fe₃Sn, Fe₃Ga, Fe₃Sb, MnCo₂As) that can have properties superior to Fe₃Si. Our results may offer guidance for future synthesis efforts aimed at discovering new and superior soft magnetic materials