Magnetic bubble collapse in ion implanted bubble propagation tracks

The magnetic-bubble collapse fields along the good, bad, and super tracks fabricated on a conventional garnet film and a nearly isotropic garnet film were measured for a cycle of rotating in-plane field. Bubble potential well curves were obtained from the bubble collapse fields and compared with each other. It was found that magnetic bubbles encounter the strongest repulsively charged walls twice during a cycle of in-plane driving field when they reside in the cusps of bad tracks. Therefore, bad tracks exhibit the shallowest potential well curves and, thus, the lowest collapse fields among the three differently oriented (good, bad, and super) tracks. When a magnetostrictively nearly isotropic film is used instead of a strongly anisotropic film, the repulsively charged walls are much weaker and the bubble potential well depths at the cusps of bad tracks become much deeper. This explains the increase of bubble collapse fields reported earlier in the bad tracks fabricated on a nearly isotropic film