Design Considerations of Permalloy Propagation Patterns for Hybrid Bubble Devices with a 2 μm Period

Bubble propagation margins along permalloy patterns on various spacer thicknesses for two types of propagation patterns, the so called half disc and wide gap patterns, were studied, and two error modes were observed. One of these was a gap error or a failure of the bubble to cross the gap, and the other was shoulder error. These errors are both caused by the spacer thickness which affects the bias magnetic field. To overcome these errors, a new pattern shape was introduced that has characteristics which are nearly independent of the spacer thickness.