Considerations on the physical interpretation of the Preisach model of ferromagnetic hysteresis

The physical meaning of the standard Preisach model (PM) and of the Preisach distribution p(α,β), particularly for what concerns the problem of the characterization of magnetic interactions, is discussed. It is shown that the standard PM can only describe interactions having a net demagnetizing effect, and that, when the factorization p(α,β)=f(α)f(−β) holds, the simple relation I_d/I_∞ = 1 − 2√I_r/I_∞, independent of f(x), exists between the Henkel plot remanences I_r and I_d. These predictions are compared with recent experimental results. Finally, the relation between magnetic interactions and hysteresis loop shapes is discussed in the frame of a generalized moving PM, where the relation between the applied field H_a and the internal PM field H is of the form H=H_a+H_i(I), where H_i(I) is an odd function of the magnetization I. The shape of p(α,β) and of H_i(I) for nonoriented SiFe alloys is determined and analyzed.