Electronic scattering from Co/Cu interfaces: In situ measurement and comparison with theory

The full thickness-dependent electrical conductivity of polycrystalline NiO /Co/Cu/Co spin-valve structures was measured in situ during ion-beam deposi tion and compared with calculations based on realistic band structure. We h ave found striking features in the experimental conductivity which are unex pected from widely used semiclassical free-electron models. Addition of sim ilar to 1 ML Co to a NiO/Co/Cu surface causes the net film conductance to d ecrease: the reverse case of Cu on NiO/Co shows a strong positive curvature of the thickness-dependent conductance, indicating a reduction of the cond uctivity in Cu near the interface with Co. Quantitative agreement is found between the experimental thickness-dependent film conductance and multiband tight-binding model calculations using a single constant parameter for on- site atomic disorder. The experimental data are consistent with strong scat tering of conduction electrons in Cu at the interfaces with Co. Comparison with theory suggests that most of the observed interface scattering may be considered to be intrinsic, arising from the placement of a high density of empty Co d states at the Cu boundaries.