Magnetization distributions, magnetostatic energy barriers, and drive fields for Permalloy bars

In an effort to understand more completely the operation of field-access bubble-domain propagation circuits, the analysis of Copeland for Permalloy thin-film elements is generalized to include the effects of a uniform in-plane drive field and applied to the problem of bubble motion along a simple bar. Results are presented for the magnetization distributions in a bar for various bubble positions and drive field situations along with the corresponding magnetostatic energy wells. The structural and spacing (Permalloy to garnet) dependence of the drive fields and the choice of garnet thickness are examined with an eye toward device optimization.