Break in the domain-wall continuity caused by a perpendicular field in toroidal ferrimagnetic polycrystals

A study of the variations of the susceptibility with a constant field applied along the axis of revolution of ring-shaped polycrystalline YIG has been made. In this sample type, where the domain-wall configuration is supposed to be toroidal, two different magnetic behaviours clearly separated by a blunt change in the susceptibility curve are brought out. They are characterized by the appearence of breaks in the initial domain-wall continuity when the perpendicular magnetic field reaches a certain threshold which announces the beginning of a rotational process of great magnitude in the perpendicular direction.