Magnetic structures: neutron diffraction studies

Neutron diffraction is often an unequivocal method for determining magnetic structures. Here we present some typical examples, stressing the sequence through experiments, data analysis, interpretation and modelisation. Two series of compounds are chosen: (a) RT2X2 (R=Rare Earth, T=3d metal and X=Si or Ge), (b) RBe13 (R=Rare Earth). Depending on the nature of the elements R,T,X, the magnetic structures produced can be commensurate or even show a transition between two such phases as a function of temperature. A model, taking magnetic exchange and anisotropy into account, will be presented in the case of commensurate-incommensurate magnetic transitions in RBe13. (orig.)