Improvement of Bubble Propagation at Conductor Crossing

The deterioration of characteristics of bubble propagation in Permalloy film at conductor pattern crossings is investigated, and means for improving propagation studied. Visual observation indicated that bubbles are trapped at crossings; conceivable reasons include 1) conductor pattern strain, 2) magnetic poles generated at steps in the Permalloy, and 3) changes in magnetization characteristics of the Permalloy. Experiments in which conductor patterns were etched away indicated that reason 3), changes in Permalloy characteristics enhanced at step regions, is responsible for the undesired bubble behavior.