ITINERANT ELECTRON FERROMAGNETISM IN FE1-XCOXSI STUDIED BY POLARIZED NEUTRON-DIFFRACTION

Polarized neutron diffraction and magnetic measurement have been carried out on single crystal samples of solid solutions Fe1-xCoxSi. 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 mu(C)/mu(s). The spin density map of Fe0.6Co0.4Si is composed of the two kinds of magnetic moments, those are, a 3d-like moment localized on the (Fe, Co) site (mu-3d) and a weak negative magnetic moment diffused over the crystal (mu(dif)). The magnetic moments are estimated to be mu-3d=0.263+/-0.014-mu(B)/(Fe, Co) atom and mu(dif)=-0.046+/-0.014-mu(B)/F.U. These results are discussed with those of typical itinerant electron ferromagnets ZrZn2, Ni3Al and MnSi.