Design and characteristics for a 4 µm period permalloy bubble device

We have developed a 4 μm period permalloy bubble propagation track, after confirming wide gap tolerance of an 8 μm period wide gap pattern reported by Bobeck et al. From the results obtained in the design and fabrication optimization of a 4 μm period permalloy track, good performance has been obtained with the following conditions: 1.3 μm bubbles, a pattern design with a wide "leg" and an "arm" of moderate length, permalloy film thickness of 3000 Å, appropriate crystal orientation and direction of DC in-plane holding field, ion implantation for hard-bubble suppression with 5 × 10¹³Ne+/cm²at 50 keV, and garnet-to-permalloy spacing of 1600 Å. Using these conditions, a 30 kbit chip has been designed and tested. Dual spacing has been introduced for chip fabrication. The major line propagation and the function operations characterized with 100 kHz triangular wave drive are found to have good performance almost the same as that of our 1 megabit device. The overall bias margin range of 20 Oe at a drive field of 65 Oe with 100 kHz triangular wave has been obtained with 10 consecutive pages.