Hysteresis of diffraction angle at the rebuilding of domain structure in magnetic films

The results of measuring the diffraction angle under the band domain structure (BDS) change in an external magnetic field H in ferrite-garnet (Bi, Lu, Y)3Fe5O12 and Dy-orthoferrite films revealing hysteresis of φn dependence are discussed. Diffraction was observed in passing light. When observing change in the doman structure in the external field it was found that variations of the BDS period are followed by motion of places of violation of the domain structure regularity - the so-called ''magnetic dislocations''. It is concluded that hysteresis in the φn dependence results from coercive ''magnetic dislocations''. It is concluded that hysteresis in the Ln(H) dependence results from coercive ''magnetic dislocations'' for the boundary field of the starting point of their motion coincides with the boundary field of measurement of the diffraction angle. The mechanism of variation of the domain structure period by motion of ''magnetic dislocations'' is peculiar for many magnetic materials having BDS