Dynamic theory of neutron diffraction on magnetic crystals

Elaborated is the dynamic theory of neutron diffraction on magnetically ordered crystals with arbitraty magnetic structure of a unit cell. Solutions of a dynamic system of equations have been obtained and a boundary problem has been considered. It is shown that the nature of dynamic scattering is qualitatively different from the case of nonmagnetic or antiferromagnetic crystals. This difference manifests itself in angular and polarization characteristics of scattered beams and in their dependence on the sample thickness and on the angle of incidence. A detailed analysis has been made for the Bragg and Laue symmetrical cases in which the secular equation of the dynamic system turns out to be biquadratic (in the Bragg case - for a random magnetic structure, and in the Laue case - in the absence of interference of nuclear and magnetic scattering). In addition Bragg reflection for thick crystals with strong magnetic birefringence is considered in detail