Wall coding for a field access bubble device

Device design and margins are given for bubble wall state coding in a field access Permalloy device. The wall states chosen to be the binary states are the S = 1 state and the S = ½, both of which have unsaturated capping layers. The 2.7 μm epitaxial (epi) garnet (YSmGdCaGe) is grown on top of a thin (0.2 μm) epi garnet (YNd GdCaGe) layer which has in-plane magnetization and is called a boot. The S = 1 state has 15 percent current margin and 20° phase margin: the S= ½ state has 45 percent current margin and 35° phase margin. The read-write bias margin is 18 Oe and is limited by the deflectometer detector.