  We studied the impact of He$^+$ irradiation on the Dzyaloshinskii-Moriya
interaction (DMI) in Ta/Co20Fe60B20/Pt/MgO samples. We found that irradiation
with of 40 keV He$^+$ ions increases DMI by approximately 20% for fluences up
to 2$\cdot$10$\rm{^{16}}$ $\rm{ions/cm}^2$ before it decreases for higher
fluence values. In contrast, the interfacial anisotropy shows a distinctly
different fluence dependence. To better understand the impact of the ion
irradiation on the Ta and Pt interfaces with the Co20Fe60B20 layer, we carried
out Monte-Carlo simulations, which showed an expected increase of disorder at
the interfaces. A moderate increase in disorder can increase the total number
of triplets for the three-site exchange mechanism and can consequently increase
the DMI. Our results demonstrate that the DMI can be locally engineered at the
nanometer scale, providing a highly promising approach to advance
skyrmion-based memories.
