STABLE PERMALLOY WIRE MEMORY ELEMENTS.
SPERRY RAND CORP PHILADELPHIA PA UNIVAC DIV
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The problem of magnetization reversal by very slow domain wall motion, generally referred to as creep, is reviewed. It is shown that the various theoretical models which have been suggested do not adequately describe all the experimental data. A versatile low frequency creep tester for cylindrical film is described. It can be used to measure critical curves, creep threshold curves, wall motion and wall nucleation field, creep velocity, and skew. The preparation of Ni-Fe films electroplated onto 5-mil Be-Cu wire is described. This includes the substrate preparation and the pre-plating of the substrate with Au to insure a smooth surface. A technique using the electron microscope which allows the direct observation of surface roughness in the cylindrical geometry is described. A general discussion of the characterization of Ni-Fe films is presented. It is concluded that the most fundamental description of a cylindrical film is obtained from biased initial susceptibility measurements. Measurements on the creep threshold as a function of thickness from 3000 Angstroms to 15,000 Angstroms are presented and the results compared to the predictions of the Olson-Torok model. It is found that the Olson-Torok model does not describe the results even in a qualitative fashion. The creep threshold is more sensitive to the wall motion field than to thickness.
- Metallurgy and Metallography
- Computer Hardware
- Electricity and Magnetism