  We show a method to control magnetic interfacial effects in multilayers with
Dzyaloshinskii-Moriya interaction (DMI) using helium (He$^{+}$) ion
irradiation. We report results from SQUID magnetometry, ferromagnetic resonance
as well as Brillouin light scattering results on multilayers with DMI as a
function of irradiation fluence to study the effect of irradiation on the
magnetic properties of the multilayers. Our results show clear evidence of the
He$^{+}$ irradiation effects on the magnetic properties which is consistent
with interface modification due to the effects of the He$^{+}$ irradiation.
This external degree of freedom offers promising perspectives to further
improve the control of magnetic skyrmions in multilayers, that could push them
towards integration in future technologies.
