Applications of a theory of ferromagnetic hysteresis

The differential equation that underlies the theory of rate-independent hysteresis for isoperm ferromagnetic materials is modified and extended to rate-dependent nonisoperm materials. The theory and its extension exhibit all of the important features of ferromagnetic hysteresis, including the existence and stability of minor loops. Both are well suited for use in numerical field-solving codes. Examples in which the material functions are simple combinations of analytic functions are presented for MnZn ferrite, NiZn ferrite, NiFe tape, and CoCr thin film. Also presented is a procedure for constructing a two-dimensional vector model that yields bell-shaped and M-shaped curves for graphs of the angular variation of the coercive field