Micromagnetics and Magnetostatics of an Iron Single Crystal Whisker

The magnetization process of an oriented iron single crystal is investigated. A solution of the micromagnetic equations for a multidomain configuration in an applied field demonstrates the dominance of magnetostatics in determining the susceptibility. The magnetic charge is found to be almost entirely on the surface, justifying the model of a fictitious medium of constant intrinsic susceptibility. This model is then used to explain the observed small coil susceptibility. Analytic expressions for the susceptibility and for an upper limit on the volume charge density (div M) are also developed. The major results of the magnetostatics calculation can be summarized by a useful local approximation for the demagnetizing field.