Validation of magnetic structures

Magnetic structures are the ordered arrays of magnetic mornents that provide the basis for our understanding of the broad range of magnetic phenomena. Neutron diffraction provides what are arguably the most inforniative data on their nature. Given synthetic difficulties in growing single crystals, powder neutron diffraction is the technique of choice for the determination of the most significant qualities of magnetic structures. The literature reveals a lot of confusion over what magnetic structures are, both in the way that magnetic diffraction data are analysed and in mistakes that are commonly made when they are represented. In this article a brief overview is given about what magnetic structures are and what steps are required in order that they be validated as 'physically reasonable'. The discussion is limited to powder diffraction.