Some characteristics of ion-implanted bubble chips

The relations between the position of charged walls and the bubble motion around propagation circuits are discussed. Long walls which extend between adjacent propagation loops are revealed by the Bitter technique. The examination of the domain structure in the implanted layer shows the existence of a magnetic gradient which is a function of the distance from the propagation circuits. The switching of magnetization in particular directions of the in-plane field is reported and correlated with the bubble movement. An additional easy axis is observed along the circuits due to shape anisotropy. Propagation margins are very similar to those obtained with permalloy circuits. Fabrication technology as well as design of 16 μm period circuits is discussed. Nucleation and transfer have been achieved with currents in the range of 50 mA to 200 mA. Phase margins of about a quarter of a period are found, and bias field margins fall between 10 and 15 Oe.