Reduction in the generate current of nucleate bubble generators by annealing

The minimum current required to generate a bubble in a hairpin-shaped aluminum nucleate generator has been found to decrease with annealing at temperatures such as those used during Permalloy deposition. This decrease, which is large and variable when the conductor is deposited directly on the bubble garnet, is associated with the build-up of stresses in the aluminum. A prespacer of SiO
2
reduces the stresses felt by the garnet and results in higher generate currents with less variability.