Figure 2. Depinning efficiency under in-plane fields in systems with varying SIA.

(a) in almost symmetric Pt(4)/Co(0.4)/Pt(2), shows a small opening between the two domain walls (red discs and blue squares) of opposite polarity, indicative of a DMI field H_D. The slope of the transition from to its saturation level is characterized by the DW anisotropy H_K. To determine these parameters, a global fit (dashed lines) is performed together with the H_y-data in (b). (c,d) Increasing the stack asymmetry by reducing the top Pt layer to 1 nm gives a higher DMI opening. (e,f) Replacing the top Pt layer by AlOx, the DMI opening becomes too large to measure in our setup. The DMI is so strong that the DW angle ϕ is hardly influenced by H_x and H_y. The fit corresponds to the average level.