  Using first-principles calculations, we investigate the impact of
hydrogenation on the Dzyaloshinskii-Moriya interaction (DMI) at graphene/Co
interface. We find that both the magnitude and chirality of DMI can be
controlled via hydrogenation absorbed on graphene surface. Our analysis using
density of states combined with first-order perturbation theory reveals that
the spin splitting and the occupation of Co-d orbitals, especially the dxz and
dz2 states, play a crucial role in defining the magnitude and the chirality of
DMI. Moreover, we find that the DMI oscillates with a period of two atomic
layers as a function of Co thickness what could be explained by analysis of
out-of-plane of Co orbitals. Our work elucidates the underlying mechanisms of
interfacial DMI origin and provides an alternative route of its control for
spintronic applications.
