Domain wall pinning by alternating materials in current-induced domain wall motion

For the application of current-induced domain wall motion, the pinning position of a domain wall must be precisely defined with a low depinning current density. A conventional way of pinning a domain wall is to use a notch which is patterned on an edge of nanostrip. As an alternative scheme of domain wall pinning, we performed micromagnetic investigation of the current-induced domain wall motion in a nanostrip with alternating materials. A segment with different magnetic parameters such as saturation magnetization, exchange constant or crystalline anisotropy can effectively pin a domain wall. It is because the segment acts as an energy barrier in the domain wall motion. Threshold current densities to depin the domain wall in nanostrips with alternating materials were of the order of 10⁸ A/cm², and can be modulated by changing the material parameters and the length of the segment.