A current-controlled disk replication useful for bubble generation

A bubble domain generator which makes possible the controlled generation of bubbles with currents of 30 mA is described. The generator is made using a single level of lithography. It uses a seed bubble on a disk, as earlier disk generators did; additionally, it incorporates a current path which inhibits or facilitates the replication of a new bubble from the seed bubble. A large current pulse of short duration may be used to initialize the seed bubble on the disk, but it should only be required a few times in the life of the memory. In 2 μm bubble devices with G, this disk replicator uses unidirectional current, exhibits phase margins exceeding ± 15°, and bias field margins greater than 15% at 40 Oe drive. It provides an alternative to hairpin nucleate generators in which much larger currents are required and to simple disk replicators in which the rotating field requirement is high. Furthermore, it requires lower currents and lower drive fields than earlier current-controlled disk replicators.