Operating Bias Field Adjustment of Bubble Propagation Tracks on Ion-Implanted Permalloy Hybrid Type Magnetic Bubble Memory Devices

Reductions in cell size of ion-implanted Permalloy hybrid magnetic bubble memory devices give rise to large differences in operating bias field regions of ion-implanted and Permalloy propagation tracks. Attempting to utilize the dependence of the operating bias field on the thickness of the bubble garnet film, the authors ion-milled films to reduce their thicknesses, thereby lowering the bubble collapse field (Ho). The ion milling was found not to change the film coercivity. In this way, by shifting the permalloy track section field margin downward by 10 Oe, the bias field regions were matched, for a larger overall (common) bias field margin.