A New Method of Propagating Domains in Thin Ferromagnetic Films

Abstract

A new mode of controlled magnetic-domain propagation has been discovered. With this technique either serrated domain boundaries or small single-wall domains can be propagated along the hard axis of an anisotropic thin film. The drive line for either case is a hairpin-shaped wire located adjacent to the film and parallel to both the film plane and the hard axis. Bipolar current pulses applied to the drive line in conjunction with a dc or pulsed hard-axis bias field are used to control propagation. The bias and drive fields are chosen to provide the necessary asymmetry for preferential propagation. Displacement of domain-wall boundaries in one direction of 2000 to 5000 Å per cycle are obtained. Both modes of propagation have been observed in 900 to 2250 Å NiFe and NiFeCo films. NiFe and NiFeCo films used for the experiments had dispersions (α90) ranging from 0.5° to 5°. Varying the film to drive-line spacing from 0.5 to 5 mil or skewing the film ±20° with respect to the drive line did not prevent domain propagation. Interpretation of these effects and experimental data defining operating conditions are given.