Controlled domain-wall injection in perpendicularly magnetized strips

For applications of domain wall (DW) motion in magnetic devices, it is vital to control the creation and position of the DW. We use Ga + irradiation of Pt/Co/Pt strips to locally change the perpendicular magnetic anisotropy. This allows us to controllably inject DWs into a device at a tunable field. The observed initial linear decrease and subsequent increase in the DW injection field upon increasing irradiation dose are explained by micromagnetic simulations and an analytical one-dimensional model.