A magnetic shift register employing controlled domain wall motion

A shift register based on controlled domain wall propagation in a magnetic wire with an axial easy direction has been developed. The operational characteristics of an experimental model are discussed. Some hard drawn magnetic materials have been shown to have at least a 3-to-1 nucleation-to-propagation threshold field window over several hundred foot lengths of wire which guarantees operation, This is accomplished without putting the wire under tension. One such promising material is a modified 79-percent Ni, 17- percent Fe, 3-percent Nb, 1-percent Ag, permalloy. An experimental
5 \times 10^{3}
-bit shift register has been constructed with 0.8-mil hard drawn Nb, Ag permalloy and operated at speeds of
5 \times 10^{3}
bps with 12-percent drive current margins. The input power at this rate is approximately 1 mW/bit.