Abstract :
Neutron scattering has progressed over the last decades to become an invaluable tool to probe experimentally condensed matter. The most widespread use of this technique is the determination of magnetic structures. In such studies, the distribution of the magnetization around magnetic atoms is usually taken from ab initio calculations. However, on a sub-atomic scale, neutron diffraction also permits the distributions themselves to be investigated. These distributions are the sum of the spin and the orbital (when present) contributions to the total magnetization. They carry precious information on the electronic structure of the sample such as the nature of the magnetic atoms, their ground state, their valency, the effects of chemical bonds (covalency), the hybridization with conduction electrons, the interactions with neighbors in the solid, the spin polarization effects , etc. Furthermore, these distributions can be directly compared to ab initio calculations and can, therefore, provide a stringent test for theory. Such studies require very precise measurements of the so-called magnetic structure factors, and, therefore, the use of polarized neutrons. In this article, an introduction to the classical polarized beam technique and to the different methods used for data analysis is made. A review of some of the latest results obtained in fields of high current interest is presented and the new developments are outlined.
