  Despite a decade of research, the precise mechanisms occurring at interfaces
underlying the Dzyaloshinskii-Moriya interaction (DMI), and thus the
possibility of fine-tuning it, are not yet fully identified. In this study, we
investigate the origin of the interfacial DMI, aiming at disentangling how
independent are the interfaces around the ferromagnetic layer, and what are
their relative contributions to the effective DMI amplitude. For this purpose,
we have grown and investigated a large variety of systems with a common
structure Pt$|$Co$|M$ with $M =$ Ni, Pd, Ru, Al, Al$|$Ta and MoSi. We explore
the correlation between the effective interfacial DMI, and different intrinsic
properties of metals, namely atomic number, electronegativity and work function
difference at the Co$|M$ interfaces. We find a linear relationship between
interfacial DMI and the work function difference between the two elements,
hence relating the nature of this behavior to the interfacial potential
gradient at the metallic interfaces. The understanding of the DMI mechanism is
of utmost importance since it opens up the possibility of precisely engineering
the magnetic and hence the spintronic properties for future devices.
