Orientation Superstructures and their Effects in Spinel Ferrites

Orientation superstructures are examined using the magnetic diffusion after-effect, the squareness ratio R, and the induced anisotropy Ku, in the ferrites: Mn0.2Fe2.8O4.014, CuxMg1−xFe2O4 (0.09 ≦ x ≦ 0.69), Mn1+xO4 (0.1 ≦ x ≦ 0.8) and Fe1.95Ni0.95Cox× × Zn0.1−xO4 (0.02 ≦ x ≦ 0.1). In the temperature zones where disaccommodation occurs (due to the ionic or electronic diffusion), a uniaxial anisotropy can be formed with a corresponding increase of R. It is shown that a new type of electron transfer: Cu+ Cu2+ is responsible for the magnetic after-effect in Mg-Cu ferrites.