Calculated electronic structure and magnetic properties of Y-Fe compounds

Abstract

Results of self-consistent ab initio band-structure calculations using the augmented--spherical-wave method are presented for the stable intermetallic compounds ${\mathrm{Y}}_{2}$${\mathrm{Fe}}_{17}$, ${\mathrm{Y}}_{6}$${\mathrm{Fe}}_{23}$, ${\mathrm{YFe}}_{3}$, and ${\mathrm{YFe}}_{2}$ and for the hypothetical compound ${\mathrm{YFe}}_{5}$. The calculated magnetic moments agree well with the experimental data, if a small orbital contribution to the total moment is assumed. The calculated equilibrium volume is systematically 6--7 % too small. This is attributed to (i) a failure of the local-spin-density-functional approximation in describing the contribution of the Fe sublattice to the total volume, and (ii) an underestimation of the contribution of the Y sublattice. The calculations explain the anomalously large volume and magnetization of ${\mathrm{Y}}_{6}$${\mathrm{Fe}}_{23}$, while the calculated magnetic moments on its four inequivalent sites agree well with neutron diffraction data. The volume dependence of the magnetization of each site in the Y-Fe compounds is related to the density of states at the Fermi level by a simple, but quite accurate expression.