Effects of Abrupt Changes in Film Thickness on Magnetic Bubble Forces

Forces on a magnetic bubble due to abrupt asymmetric changes in the surface configuration of the magnetic film are investigated theoretically and experimentally. A model is derived for calculating the forces on a bubble as it is being moved by conductor propagation through a thickness gradient in the film. An experiment is described in which the forces necessary to move a bubble through this transition region are measured and compared with predicted values computed from the model. Results are presented for a 20° gradient with a cut 0.62 µm deep in a garnet film, nominally 3.8 µm thick, prepared by liquid phase epitaxy.