MAGNETIC STRUCTURE AND SPIN-DENSITY DISTRIBUTION IN UFE2

A study has been made by the diffraction of polarized neutrons of a single crystal of the ferromagnetic compound UFe2 at 84°K (T/T C = 0.49). The flipping ratios of all reflections out to a sinθ/λ value of 0.41 A-1 have been measured. These measurements show that, at this temperature, the Fe atom has a magnetic moment of 0.38 μB and that there is a small but significant moment of the U atom, parallel to the Fe moment, of about 0.03 μB. The spin density distribution at the U atom position is very nearly spherically symmetric, but the spin density at the Fe site is seen to have large deviations from spherical symmetry, being elongated in the direction of the cube edges and contracted along the nearest-neighbor connecting line. Good agreement between observed and calculated structure factors is obtained by using a shallow form factor of the 5f3 type for the U moment, and by using an Fe form factor calculated on the basis of 65% of the magnetic electrons having E g symmetry and 35% T2g symmetry. © 1969 The American Institute of Physics.