  A new technique for estimation of magnetic interaction effects of initial
magnetization curves has been proposed. It deals with remanence, and initial
irreversible magnetization, curves. The method is applied for single-phase
polycrystalline Ni0.85-xCu0.15ZnxFe2O4, (x = 0, 0.2, 0.4 and 0.6), which were
synthesized by a standard ceramic technology. A study of the initial reversible
and irreversible magnetization processes in ferrite materials was carried out.
The field dependence of the irreversible, and reversible, magnetizations was
determined by magnetic losses of minor hysteresis loops obtained from different
points of an initial magnetization curve. The influence of Zn-substitutions in
Ni-Cu ferrites over irreversible magnetization processes and interactions in
magnetic systems has been analyzed.
