Susceptibility Measurements and the Magnetocrystalline Anisotropy of Polycrystalline Ferromagnetic Films

This paper reports a comparison of observations of the transverse susceptibility with some ripple theories due to a number of authors. A very wide range of films was investigated. It is demonstrated that these theories are qualitatively successful in relating macroscopic magnetic observables to single crystal magneto‐crystalline and magneto‐elastic effects. However, quantitative comparisons require unreasonably large values of magneto‐crystalline anisotropy K 1 to fit the observations in cases where magneto‐elastic effects should be negligible. Better fits to the observations and more reasonable values of K 1 are obtained for a ripple field theory of the type described by Feldtkeller, but in which the power of the field dependence of the susceptibility is allowed to vary for different films. Such behaviour is consistent with a two‐component model of the magnetization ripple, the properties of which are briefly outlined.