Nickel on lead, magnetically dead or alive?

Two atomic layers of Ni condensed onto Pb films behave, according to anomalous Hall effect measurements, as magnetic dead layers. However, it has been observed that sub-monolayers of Ni lower the superconducting transition temperature of the Pb film. This has lead to the conclusion that the Ni atoms are still very weakly magnetic and that their magnetic scattering causes the reduction of the transition temperature. In the present paper the electron dephasing due to the Ni has been measured by weak localization. The dephasing is smaller by a factor 100 than the T c -reduction would suggest. This proves that the T c -reduction in the PbNi films is not due magnetic Ni moments.