High-frequency propagation and failure of contiguous disk magnetic bubble devices

Abstract

High-frequency propagation and failure of contiguous disk devices in an ion-implanted 3-μm YSmLuCaGe garnet film were investigated by using high-speed optical sampling. The minimum drive field, the bias field operating margin, and the bubble position with respect to the instantaneous rotating field direction were found to change with the frequency of the drive field. The shape and position of bubbles during the propagation were measured so that the instantaneous velocity dependence of the frequency of the drive field could be calculated. This study was done on a selection of different tracks so that the dependence of the geometry of the tracks could be included. It was found that more uniform instantaneous velocity leads to lower minimum drive field and a higher rotating frequency limit. The cause of high-frequency failure was examined and found generally to be the limitation of the maximum velocity of bubbles causing a phase lag greater than 90°. This limitation can be caused either by a low drive or by a saturation velocity.

Magnetic bubble domain devices

“…In contrast to this fine space resolution and rather coarse time resolution, the high-speed microscope is most easily directed towards very fine time resolution and rather poor space resolution. For this reason, we may find research being conducted with abnormally large bubble domains on specially built bubble devices and at rather artificially high speeds (Zhang and Humphrey 1982). This, at least, illustrates the special problems of device dynamics, but also underlines the need for considerably more work in this area with the kind of magnetic bubble memory devices which are actually used in computer systems.…”