Flux Reversal in Soft Ferromagnetics

Abstract

Many aspects of flux reversal in soft ferromagnetic materials may be interpreted in terms of three types of flux reversal processes. These three types are domain wall motion, nonuniform rotation, and uniform rotation. It has been shown that in general wall motion is the predominant mechanism for values of the applied magnetic field slightly in excess of the coercive field, that nonuniform rotation predominates for intermediate magnetic fields, and that uniform rotation predominates for large fields. The salient features of these three types of flux reversal are discussed and compared with experimental findings. Special emphasis is given to polycrystalline, square-looped ferrites, and thin Permalloy films. The importance of geometric effects is illustrated in a review of detailed models for the uniform and nonuniform rotational processes. Specific limitations of the existing models are discussed, and possibilities for future advances are briefly outlined.