Simulation of Magnetization Reversal and Domain-Wall Trapping in Submicron Permalloy Wires With Different Wire Geometries

Nonvolatile data storage in today´s computers is based on magnetic materials. Hard disk drives (HDD) feature ferromagnetic thin films for recording bits as regions with different magnetizations in the film. At present, the efforts of decreasing HDD size while increasing storage capacity, however, face fundamental limits, namely, the so-called superparamagnetic effect. Research into new generations of magnetic data-storage devices, amongst others, considers as its basic working principle current-induced magnetic domain-wall motion (CIDWM) in magnetic nanowires. In this paper, we present simulation studies of external magnetic field-induced magnetization reversal and domain-wall motion in nanowires of various sizes and shapes. Our results contribute to the basic design principles applied to magnetic structures used in CIDWM experiments. Parameters, such as wire thickness and wire-pad geometries are investigated, and important threshold magnetic field values are presented. In addition, we introduce a novel method of domain-wall trapping in a magnetic wire using the fringe fields of close-by magnets.