Effect of composition and composition inhomogeneity on the strain sensitivity of plated wire memory elements.

An analysis was made of the relation between the strain sensitivity of plated wire memory elements and the chemical composition in the film. According to this analysis, torsion sensitivity, which measures the easy-axis skew when the wire is twisted, depends on the average permalloy composition in the film. On the other hand, tension sensitivity, which measures the change in anisotropy field, H , when the wire is stretched, should depend on both the average composition and the degree of variation, or composition inhomogeneity. In general, the inhomogeneity contribution is negative. Experimental results supporting this analysis showed that 1) films with nearly zero torsion strain sensitivity invariably exhibit negative tension strain sensitivity and 2) the measured tension strain sensitivity is in approximate agreement with that predicted from electron microprobe measurements of composition inhomogeneity. The strain sensitivity analysis provides a means of estimating the discrepancy between torsion and tension zeromagnetostrictive compositions. [ABSTRACT FROM AUTHOR]