Electronic structures of FeB,Fe2B, andFe3B compounds studied using first-principles spin-polarized calculations

The band structures of the ferromagnetic compounds FeB, ${\mathrm{Fe}}_2$B, and ${\mathrm{Fe}}_3$B were calculated using a spin-polarized version of the first-principles self-consistent orthogonalized linear-combination-of-atomic-orbitals method. Results on the band structure, density of states (DOS), and site-, orbital-, and spin-decomposed partial DOS are presented. Mulliken population analysis indicates B to be an electron accepter in these compounds due to the low-lying levels of the B 2s and B 2p states relative to the Fermi level. It is also shown that the moment on B is slightly polarized opposite to the Fe moments. The magnetic structure and bonding in these three compounds are further revealed by the presentation of contour maps for the charge density and the spin density. Our calculation shows an average spin magnetic moment of 1.26, 1.95, and 1.94${\mathrm{\mu }}_{\mathit{B}}$ per Fe site and -0.10, -0.23, and -0.29${\mathrm{\mu }}_{\mathit{B}}$ per B site in FeB, ${\mathrm{Fe}}_2$B, and ${\mathrm{Fe}}_3$B, respectively. The results are in reasonable agreement with photoemission and neutron-scattering measurements. The nature of the Fe-B bond is discussed in connection with the electronic structure of ${\mathrm{Nd}}_2$ ${\mathrm{Fe}}_{14}$B intermetallic compounds and that of the ${\mathrm{Fe}}_{1\mathrm{-}\mathit{x}}$ ${\mathrm{B}}_{\mathit{x}}$ metallic glasses.