  The quantitative roles of the interfacial spin-orbit coupling (SOC) in
Dzyaloshinskii-Moriya interaction (DMI) and dampinglike spin-orbit torque
({\tau}DL) have remained unsettled after a decade of intensive study. Here, we
report a conclusive experiment evidence that, because of the critical role of
the interfacial orbital hybridization, the interfacial DMI is not necessarily a
linear function of the interfacial SOC, e.g. at Au1-xPtx/Co interfaces where
the interfacial SOC can be tuned significantly via strongly composition
(x)-dependent spin-orbit proximity effect without varying the bulk SOC and the
electronegativity of the Au1-xPtx layer. We also find that {\tau}DL in the
Au1-xPtx/Co bilayers varies distinctly from the interfacial SOC as a function
of x, indicating no important {\tau}DL contribution from the interfacial
Rashba-Edelstein effect.
