Small-angle critical magnetic scattering of neutrons in iron

Measurements of the temperature variation of small-angle critical scattering of 1.25 Å neutrons by iron were performed. Taking into account the inelasticity of the scattering, the parameters which define the instantaneous spin correlation function of the Ornstein-Zernicke type were determined. This form of the function turned out to be valid at distances larger than 15–20 Å. For smaller distances, it has been confirmed that the instantaneous correlation function has the form of a simple exponential. From the data for T − Tc ⩾ 10° it has been deduced that the temperature variation of the static magnetic susceptibility is of the form (T − Tc)−(1.30 ± 0.04).