Spin flipping at sputtered Co/Ag interfaces

We measured at 4.2 K the current-perpendicular-to-plane magnetoresistances of sputtered ferromagnetically coupled [Co(3 nm)/Ag(1.8 or 2.0 nm)]${}_{n}$Co(3 nm) multilayers with $n$ = 0--8 that were imbedded in the middle of symmetric, Py-based, double exchange-bias spin valves. The measurements yielded the parameter for spin flipping at the Co/Ag interface, ${\ensuremath{\delta}}_{\mathrm{Co}/\mathrm{Ag}}$ = 0.33\ifmmode\pm\else\textpm\fi{}0.1. Despite the expected larger lattice-mismatch-induced disorder at the Co/Ag interface, this value is similar to that reported earlier for the Co/Cu interface, suggesting that such disorder does not play a major role in \ensuremath{\delta} for these metal pairs.