Rectangular Hysteresis Loop Ferrites with Large Barkhausen Steps

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Abstract
Observations have been made at low temperatures of large discontinuities (steps) in the 60-cycle hysteresis loops of polycrystalline ferrites containing copper. At the temperature for step formation, which is a function of copper content, the coercivity decreases and the loop squareness approaches unity. This behavior is attributed to the formation (in the toroidal specimens used) of circular 180° domain walls having different threshold fields. This domain wall configuration is probably brought on at low temperatures by a low effective magnetocrystalline anisotropy provided by the localized distortions exerted by divalent copper in the spinel lattice.