ON MEASURING THE NEUTRON SCATTERING FORM FACTORS ASSOCIATED WITH SPIN WAVES

摘要

A value for this ratio may also be obtained from data on the temperature variation of the saturation magnetisation¹ and the numerical value² derived on this basis appears to be about 15. Thus, R²/ρ² is certainly >> 1 for nickel and may well approach a figure of order 100. It seems that similar conditions may also obtain in iron and iron-nickel alloys.nAs pointed out by Marshall¹ the implication of long range exchange interactions contained in the above results suggests the use of the concept of Slater type spin waves for the metals concerned. Such a spin wave can be thought of as a region of reduced spin propagating with a given wave vector q. Information as to the spatial extent of this spin unit could be obtained by neutron scattering experiments in which the form factor corresponding to scattering from spin waves is observed.