Millimicrosecond Switching Properties of Ferrite Computer Elements

An examination of the switching properties of square loop ferrites is presented. Switching times have been studied over the range 5 μsec to 10 mμsec. The switching parameters, threshold field and switching constant, have been studied as a function of temperature and of ceramic processing. The plot of inverse of switching time versus applied fields displays three nearly linear portions for which the slopes vary by a factor of from two to ten. The inverse slope known as the switching constant of the material has therefore three values; this is interpreted as indicating three mechanisms to be responsible for the process of flux reversal, each mechanism being dominant over a certain region of the switching curve. These mechanisms are proposed as being wall motion, incoherent rotation, and coherent rotation. A model allowing a coherent rotation process is proposed. Data are presented for several ferrites which have widely varying properties.