On the origin of magnetic anisotropy in 4f-free ferromagnets based on the CaCu5structure.

Using first-principles calculations, we investigate the origin of magnetocrystalline anisotropy in a series of 4f-electron-free intermetallics with CaCu₅-based structures: YCo₅, YCo₄B, and Y₃Co₁₃B₂. The electronic structure of these compounds is characterized by a set of narrow 3dbands near the Fermi level. In YCo₅the easy-axis anisotropy originates primarily in the spin-orbit coupling-induced mixing of the electronic states with Codx2-y2anddxycharacter. The analysis ofk-resolved anisotropy shows that positive contributions accumulate from the entire Brillouin zone but are particularly large near thekz=0plane. The analysis of the single-site and two-site terms reveals a large positive single-site contribution to the magnetocrystalline anisotropy from the Co atoms on the honeycomb sublattice, along with two-site contributions from both honeycomb and kagome sublattices.