On the theory of the dispersion of magnetic permeability in ferromagnetic bodies

This chapter examines the distribution of magnetic moments in a ferromagnetic crystal. When the crystal is magnetized, the boundaries between the oppositely magnetized layers move so that the layers with one direction of magnetic moment grow at the cost of the layers with moments in the opposite direction. The presence of separate elementary regions, magnetized in opposite directions, is due only to the demagnetizing effect of the surface, and the number and dimensions of these regions are entirely determined by the dimensions of the body. The analysis of the preceding section gives only the distribution of the directions of the magnetic moments in the intermediate regions but gives nothing for determining the width of the layers. If the crystal is placed in an external magnetic field, which is directed parallel to the axis of easiest magnetization, the boundaries between the layers begin to move so that the layers with magnetic moments parallel to the field become wider.