  Magnetization reversal and domain wall dynamics in Pt/Co/AlOx trilayers have
been tuned by He+ ion irradiation. Fluences up to 1.5x10$^{15}$ ions/cm$^2$
strongly decrease the perpendicular magnetic anisotropy (PMA), without
affecting neither the spontaneous magnetization nor the strength of the
Dzyaloshinskii-Moriya interaction (DMI). This confirms the robustness of the
DMI interaction against interfacial chemical intermixing, already predicted by
theory. In parallel with the decrease of the PMA in the irradiated samples, a
strong decrease of the depinning field is observed. This allows the domain
walls to reach large maximum velocities with lower magnetic fields with respect
to those needed for the pristine films. Decoupling PMA from DMI can therefore
be beneficial for the design of low energy devices based on domain wall
dynamics. When the samples are irradiated with larger He+ fluences, the
magnetization gets close to the out-of-plane/in-plane reorientation transition
where 100nm size magnetic skyrmions are stabilized. We observe that as the He+
fluence increases, the skyrmion size decreases while these magnetic textures
become more stable against the application of an external magnetic field.
