Dynamic conversion during magnetic bubble domain wall motion

Abstract

The experimentally and previously observed erratic propagation of an individual magnetic bubble domain during repetitive bubble transport measurements has been attributed to the dynamic conversion of a normal bubble domain wall into a relatively immobile state. A model for dynamic conversion is presented in this paper. The model extends previous work of Slonczewski and Thiele and suggests that the immobile wall state contains both moving horizontal Bloch lines and stationary vertical Bloch lines, the latter of which are parallel with the cylindrical axis of the bubble domain. The model accounts qualitatively for the evolution of this state from a normal bubble and for its return to the normal bubble state when motion ceases. Interactions between the moving domain wall and material inhomogeneities are postulated to be important in initiating dynamic conversion, and it is suggested that the erratic characteristics associated with dynamic conversion arise from the statistical nature of these interactions. Methods of suppressing dynamic conversion are discussed. The three most important methods appear to be to restrict bubble domain velocities to values below a critical value, to use a large in‐plane anisotropy, or to employ a special three‐layer structure in which the bubble domain wall becomes dynamically stabilized against dynamic conversion.