Conduction electron scattering and spin flipping at sputtered Co/Ni interfaces

Abstract

Current-perpendicular-to-plane magnetoresistance (CPP-MR) measurements let us quantify conduction electron scattering and spin flipping at a sputtered ferromagnetic/ferromagnetic $(\text{F}1/\text{F}2=\text{Co}/\text{Ni})$ interface, with important consequences for CPP-MR and spin-torque experiments with perpendicular anisotropy. We use ferromagnetically coupled ${[\text{Ni}/\text{Co}]}_{n}\text{Ni}$ multilayers, and Py-based, symmetric double exchange-biased spin valves containing inserts of ferromagnetically coupled ${[\text{Co}/\text{Ni}]}_{n}\text{Co}$ or ${[\text{Ni}/\text{Co}]}_{n}\text{Ni}$ multilayers, to derive Co/Ni interface specific resistances $A{R}_{\text{Co}/\text{Ni}}^{\ensuremath{\uparrow}}={0.03}_{\ensuremath{-}0.03}^{+0.02}\text{ }\text{f}\ensuremath{\Omega}\text{ }{\text{m}}^{2}$ and $A{R}_{\text{Co}/\text{Ni}}^{\ensuremath{\downarrow}}=1.00\ifmmode\pm\else\textpm\fi{}0.07\text{ }\text{f}\ensuremath{\Omega}\text{ }{\text{m}}^{2}$, and interface spin-flipping parameter ${\ensuremath{\delta}}_{\text{Co}/\text{Ni}}=0.35\ifmmode\pm\else\textpm\fi{}0.05$. The specific resistances are consistent with our no-free-parameter calculations for an interface thickness between 2 and 4 monolayers that is compatible with expectations.