A physical model of spin ferromagnetism

This paper derives a mathematical model for the hysteresis characteristics of spin-ferromagnetic materials on a quantum-mechanical basis. For a given material, the model provides a link between the micromagnetic behavior at the atomic/domain levels and the details of the scalar hysteresis loop at the macroscopic level. Physical input parameters of the model consist of the Curie temperature, the sample temperature, the saturation magnetization, and the intrinsic coercivity. The parameters of the mathematical model are the reduced temperature t, the Weiss coefficient α, a new quantity called the domain coefficient β, and a single pinning coefficient γ that defines the anhysteretic magnetization. Quantitative agreement with the measured hysteresis data of a wide range of materials, including temperature dependence, is good. The model is valid for materials with intrinsic coercivities ranging over 6 orders of magnitude.