Moving preisach model analysis of nanocrystalline SmFeCo

Nanocrystalline SmFeCo, prepared by mechanically alloying the elementary powders and subsequent annealing (600 degrees C/15 min), showed remanence enhancement (eta=I-r/I-s=0.67) and H-c= 18.6 kOe. Starting from the ac-demagnetized state, minor hysteresis loops were determined for magnetic fields up to 70 kOe for numerical calculation of the Preisach function p(h(c),h(u)), where h(c) and h(u) are the elementary loop coercive field and interaction field. The numerically determined irreversible part of p(h(c),h(u)) had a form indicating that it could be factored: p(irr)(h(c),h(u))=f(h(c))g(h(u)), where f(h(c)) and g(h(u)) are log-normal and Gaussian distributions. An analytic expression for p(h(c),h(u))=f(h(c))g(h(u)) + P-rev was fitted to experimental hysteresis curves. The analytic expression for p(h(c),h(u)) was used with the moving Preisach model to calculate minor loops and Henkel plots. Agreement between theory and experiment was very good. (C) 1997 American Institute of Physics.