The effect of overlay stress on the uniaxial anisotropy of garnet bubble domain films

In the overlay films used for bubble domain propagation circuitry elastic energy is stored. Some of this energy is transferred to the LPE garnet film and because of the magnetoelastic coupling, significant alterations can be caused in the uniaxial anisotropy, Ku. The amount of elastic energy stored in the overlay is typically proportional to the product of the film stress and the film thickness. The elastic energy transferred to the garnet film is via surface tractions at the interface of the garnet and the overlay films. By assuming as boundary conditions that these surface tractions are uniform underneath the overlay and zero outside of the overlay boundaries, it has been possible to calculate from elasticity theory the stress distribution in the garnet film and substrate.The results show that the most severe alterations in Kuoccur at the edges of the overlay. Underneath the overlay the changes in Kuare less severe.