Magnetocrystalline anisotropy of the Fe-sublattice in Y₂Fe ₁₄B systems

To reveal the role of Fe sublattice in the coercivity of R ₂Fe₁₄B, we investigated the origin of perpendicular magnetocrystalline anisotropy (MCA) of Y₂Fe₁₄B using first-principles density-functional calculations. We found that the perpendicular MCA of Y₂Fe₁₄B arises predominantly from Fe sites with higher symmetry (16k_1,2 and 8j_1,2). On the other hand, the Fe(4c) sites show a significant contribution to the in-plane MCA. This can be attributed to the localized character of Fe(4c)-d orbitals in R₂Fe₁₄B. Furthermore, the MCA energy of Y ₂Fe₁₄B increases as the number of valence electrons increases within the rigid band model, indicating that the partial substitution of Fe by Co can enhance the MCA energy of Y₂Fe₁₄B.