Usefulness of the group theory in the magnetic structure determination

This paper contains an overview about the use of the group theory representation analysis in the magnetic structure resolution. Firstly, a description about the different types of magnetic structures which are usually found in solids below the order temperature is given. Secondly, some important concepts which are necessary in the analysis are introduced, as the star of q-vector and the small group Gq-vector. Thirdly, it has been shown the method that must be followed in order to find out the possible magnetic structures which are compatible with the symmetry of the crystal. These concepts are illustrated with the example of the magnetic structure of YMnO3 perovskite. Finally, it has been shown that, in certain cases it can be an advantage also to consider the time inversion element. In this case it must be taken into consideration the group theory corepresentation analysis.(author)