Modeling of transfer gates in ion-implanted bubble devices

In-plane domain structures of rudimentary transfer gates for 2μm bubble devices are calculated by numerical minimization of energy. Results are compared with failure mechanisms observed through high speed optical sampling techniques. Insights into the formation of charged walls are obtained in addition to general design rules for such gates. A uniaxial anisotropy term along the pattern edge was found necessary for the general formation of charged walls, as was previously suggested. The need for this term is especially apparent when the applied field is directed along an easy magnetization direction, a condition that occurs in the model transfer gates. The experimental study shows that small local radii of curvature for both the major and minor loop elements result in lower minimum drive fields. Also, positioning the major loop cusp far from the minor loop element reduces the loss of low bias margin that results from strip-out.