Magnetic space groups.

Magnetic space groups (MSGs) were first introduced (under a different name) by Heesch more than 30 years ago, and a list of all of them was published by Belov, Neronova and Srairnova in 1955. However, no mathematically rigorous derivation of MSGs can be found in the existing literature, although an outline of a method for obtaining a large class of MSGs was published by Zaraorzaev in 1957. In this thesis a systematic rigorous method for constructing MSGs is described in detail, and a proof that the method in fact gives all the MSGs is presented. The method also leads in a natural way to a classification of MSGs which is useful for a systematic study of the arrangements of spins in ferromagnetic, ferrimagnetic and antiferromagnetic crystals. The first and the last chapter of the thesis deal with the physical aspects of the problem, the remaining chapters with purely mathematical aspects of it.Science, Faculty ofPhysics and Astronomy, Department ofGraduat