Gradientless propulsion of magnetic bubble domains

Abstract

Magnetic bubble domains are propagated in a magnetic medium in a desired direction using magnetic fields which have no spatial gradients. This is in contrast with conventional propagation techniques where magnetic overlays have to be used with applied magnetic fields in order to move domains. Depending upon the wall magnetization configurations in the domains, these domains are propagated by using, for example, a combination of a steady magnetic field and a magnetic field which varies with time, such as a pulse field or a sinusoidal field. This type of propagation is termed automotion. Bubbles which can automote are generated and detected in the magnetic medium using the principles of automotion. Embodiments are shown for representation of information using different types of bubbles, and in particular it is shown how to discriminate among bubble domains having wall configurations having a common winding number s. In a particular embodiment, a modulated bias field is superimposed on a steady magnetic field in the plane of the magnetic medium. Depending upon the direction of the in-plane magnetic field and upon the wall magnetization configuration of the bubbles, the bubbles can be made to move in different directions regardless of the directions of the modulated bias field.