Designs and Characteristics of 2 μm Period Ion-Implanted Propagation Tracks

The effect of the shape of ion-implanted (into YSmLuCaGeIG) propagation tracks on the operating margin in bubble memory devices were studied. A snake pattern was used, with a period of 2 μm and pattern width of 0.7 μm, varying the cusp angle θ (i.e., the cusp depth). The cusp angle dependencies of bias margin width (50 Oe drive) and minimum drive field indicated that for a single loop, the smaller the cusp angle, the better the margin. However consequent reduction of the distance between adjacent cells led to jumping errors, and the optimum margin occurred for θ = 90°. A minimum drive field of 58 Oe and bias margin width of 48 Oe (70 Oe drive) were obtained.