On the Magnetocrystalline Anisotropy of NiCo Ferrites

The magnetocrystalline anisotropy of Co x Ni 1− x Fe 2 O 4 ± γ is measured at room temperature by torque measurements. It is found that an additional couple caused by the anisodropy of the magnetization must be taken into account in the determination of the magnetocrystalline constants. For the (100)‐plane is found that the magnetocrystalline anisotropy increases nearly linearly with the Co‐content. The constants k 1 of the anisotropy of the magnetization also increase linearly at low Co‐additions, but at higher Co‐concentrations the increase is less than linear. Measurements in the (111)‐plane show a marked dependence of L max on the magnetic field strength. Attempts to find the values of the constants by extrapolation prove unsuccesful.