Optimization of Permalloy and Iron Notched Nanowires with Domain Wall Pinning Geometries for Use with Magnetic Memory Devices

摘要

Micromagnetic simulations were carried out to optimize the domain wall (DW) forming properties of 20 nm thick permalloy and iron nanowires for use in magnetic memory technologies. These had two pairs of notched pinning sites and the relative position of the notches and the pinning site geometry were found to affect the DW formation under perpendicular magnetic fields. Simulations of 600 nm wide nanowires were performed which had equilateral triangular notches and twin pinning sites with center distances ranging between 0.5 μm and 1.4 μm. In order to develop this technology for memory devices we investigated the DW formation at the remanent state by controlling the pinning geometry and the degree of notch offset at the pinning sites in order to see if a useful configuration could be found. Various notch depths and off-sets were simulated in order to modify the DWs for future data storage technologies. Investigation of the longitudinal easy-axis magnetization indicated that no DWs were produced on the pinning sites when at the remanent state. However, the perpendicularly applied fields produced several potentially useful DW configurations including vortex DWs whose chirality could be engineered by controlling notch and pinning site geometry. We conclude that twin pinning sites are potentially very useful for magnetic memory device applications.