The observation of domain structure in bubble propagation circuits

Abstract

The generation, propagation and detection of bubble domains in conventional field access bubble devices is controlled by changes in the domain structure of the Permalloy overlay elements in a rotating magnetic field. A technique for observing related changes using Lorentz microscopy is described and some results obtained for specimens taken from a T and I bar overlay structure and subjected to small DC magnetic fields are discussed. In suitable cases the technique could be extended to situations where the interaction of the bubble domains and the overlay might be observed.