Distribution of Magnetic Moment in Hexagonal Cobalt

The magnetic form factor of hexagonal cobalt has been determined by measuring the coherent scattering of a polarized neutron beam from single-crystal samples. A Fourier inversion of the data indicates a nearly spherical distribution of positive moment around each atom, decreasing to a negative level in the space between atoms. A comparison of the results with calculated free-atom form factors shows that the observations can be accurately described by a model in which the net spin density is given by the sum of a positive free-atom $3d$ distribution and a negative constant. In terms of this model, the total moment per atom is composed of the following parts: $3d$ spin, + 1.86±0.07 μβ; $3d$ orbital, + 0.13±0.01 μβ; constant spin, -0.28 ±0.07μβ. The form factor showed no dependence on temperature between 78 and 300°K.