Magnetocrystalline Anisotropy and Magnetic Permeability of Mn-Zn-Fe Ferrites

Magnetocrystalline anisotropy was measured for Mn-Zn-Fe ternary ferrites from liquid oxygen temperature to the Curie point by means of torque magnetometer, using a number of monocrystals. Anisotropy constant K 1 increases monotonically from that of the pure Mn ferrite with the increase of the content of ZnO. On the other hand, the introduction of a small amount of ferrous ions into Mn-Zn ferrites has a remarkable effect of increasing K 1 in positive sense. It was found that there is a region of exhibiting a positive K 1 at room temperature in the Mn-Zn-Fe ternary diagram. A feature of the temperature dependence of permeability µ can be interpreted in terms of a thermal change of K 1 The origin of the second maximum in µ versus T curve which is often observed near room temperature for many Mn-Zn ferrites is considered to be corresponding to the point of K 1 =0. The compositional dependence of the permeability is interpreted from those of the magnetocrystalline constant and the Curie point.