Itinerant Electron Ferromagnetism in Fe_1−xCo_xSi Studied by Polarized Neutron Diffraction

Abstract

Polarized neutron diffraction and magnetic measurement have been carried out on single crystal samples of solid solutions Fe_1−xCo_xSi. The result of magnetic measurement shows that this alloy has a lot of features of itinerant electron ferromagnet i.e. low T_C, small magnetization, large value of μ_C⁄μ_s. The spin density map of Fe_0.6Co_0.4Si is composed of the two kinds of magnetic moments, those are, a 3d-like moment localized on the (Fe, Co) site (μ_3d) and a weak negative magnetic moment diffused over the crystal (μ_dif). The magnetic moments are estimated to be μ_3d=0.263±0.014μ_B/(Fe, Co) atom and μ_dif=−0.046±0.014μ_B/F.U. These results are discussed with those of typical itinerant electron ferromagnets ZrZn₂, Ni₃Al and MnSi.