  Following the discovery of topological insulators, there has been a renewed
interest in superconducting systems that have strong spin-orbit (SO) coupling.
Here we address the fundamental question of how the spin properties of a
otherwise spin-singlet superconducting ground state evolve with increasing SO
impurity density. We have mapped out the Zeeman critical field phase diagram of
superconducting Al films that were deposited over random Pb cluster arrays of
varying density. These phase diagrams give a direct measure of the Fermi liquid
spin renormalization, as well as the spin orbit scattering rate. We find that
the spin renormalization is a linear function of the average Pb
cluster-to-cluster separation and that this dependency can be used to tune the
spin susceptibility of the Al over a surprisingly wide range from 0.8$\chi_0$
to 4.0$\chi_0$, where $\chi_0$ is the non-interacting Pauli susceptibility.
