The theory of elastic scattering of neutrons by magnetic salts

Abstract

The use of elastic neutron scattering to examine the magnetic structure and electronic distribution in nonmetallic materials has increased rapidly in the last few years. Unfortunately, techniques for analysing the results have not always kept pace with the complexity of the crystals. A rather confusing situation has arisen whereby two apparently unrelated approaches to the analysis problem exist. The traditional approach is to express the scattering interaction as a vector operator. For simple systems this is ideal, but it is not easy to apply to a complicated wave function involving both spin and orbital magnetization, or if the direction of magnetization is not simply related to other principal directions in the experiment. As a result, an alternative approach using tensor operators has been introduced that will handle a much wider range of systems. It is based on a rather elaborate formalism and the answers appear in a different form from the traditional method.