  The search for chiral magnetic textures in systems lacking spatial inversion
symmetry has attracted a massive amount of interest in the recent years with
the real space observation of novel exotic magnetic phases such as skyrmions
lattices, but also domain walls and spin spirals with a defined chirality. The
electrical control of these textures offers thrilling perspectives in terms of
fast and robust ultrahigh density data manipulation. A powerful ingredient
commonly used to stabilize chiral magnetic states is the so-called
Dzyaloshinskii-Moriya interaction (DMI) arising from spin-orbit coupling in
inversion asymmetric magnets. Such a large antisymmetric exchange has been
obtained at interfaces between heavy metals and transition metal ferromagnets,
resulting in spin spirals and nanoskyrmion lattices. Here, using relativistic
first-principles calculations, we demonstrate that the magnitude and sign of
DMI can be entirely controlled by tuning the oxygen coverage of the magnetic
film, therefore enabling the smart design of chiral magnetism in ultra-thin
films. We anticipate that these results extend to other electronegative ions
and suggest the possibility of electrical tuning of exotic magnetic phases.
