  We have systematically introduced charged impurity scatterers in the form of
Mg adsorbates to exfoliated single layer graphene and observe little variation
of the spin relaxation times despite pronounced changes in the charge transport
behavior. All measurements are performed on non-local graphene tunneling spin
valves exposed in-situ to Mg adatoms, thus systematically introducing
atomic-scale charged impurity scattering. While charge transport properties
exhibit decreased mobility and decreased momentum scattering times, the
observed spin lifetimes are not significantly affected indicating that charged
impurity scattering is inconsequential in the present regime of spin relaxation
times.
