Minimum drive fields in contiguous-disk bubble devices

The shape anisotropy resulting from the elongated, parallel arrangement of the propagation tracks in contiguous-disk bubble devices makes a significant contribution to the minimum drive field of these devices. A simple model relates this contribution to the minimum drive field with the demagnetizing field of the ion-planted region between adjacent propagation tracks. There is good agreement between the prediction of the model and published results on eleven different contiguous-disk bubble devices. The implications on drive field requirements as contiguous-disk devices are scaled to high storage density are briefly considered.