Calculatedsp-electron andspd-hybridization effects on the magnetic properties of smallFeNclusters

The ground-state magnetic properties and related electronic properties of small ${\mathrm{Fe}}_{\mathit{N}}$ clusters are calculated by using an spd-band model Hamiltonian in the unrestricted Hartree-Fock approximation. Results are given for the average magnetic moment per atom μ${\mathrm{¯}}_{\mathit{N}}$, the spin-polarized charge distribution within the cluster, and the sp and d electronic density of states. The calculated μ${\mathrm{¯}}_{\mathit{N}}$ (N≤15) are larger than the bulk value ${\mathrm{\mu }}_{\mathit{b}}$=2.21${\mathrm{\mu }}_{\mathit{B}}$. Small local sp magnetic moments are obtained, which in most cases are opposite to the dominant d magnetic moments (${\mathrm{\mu }}_{\mathit{s}\mathit{p}}$≃-0.1${\mathrm{\mu }}_{\mathit{B}}$, ${\mathrm{\mu }}_{\mathit{d}}$≃2.5–2.9${\mathrm{\mu }}_{\mathit{B}}$). The role of sp electrons and spd hybridization is discussed particularly, by comparison with previous d-band model calculations. The main quantitative effect obtained by including the sp electrons in the self-consistent calculations is a reduction of about 10% of the value of μ${\mathrm{¯}}_{\mathit{N}}$.