Correlation between quantum-size effects in the giant magnetoresistance and interlayer coupling in magnetic multilayers

Interlayer exchange coupling and quantum-size effects in the dependence of the giant magnetoresistance on the spacer thickness $d$ in magnetic trilayers are shown to be correlated. It is shown that the relative resistance change due to the magnetization rotation has a component that oscillates with increasing spacer thickness with exactly the same oscillation period as that found in the $d$ dependence of the coupling parameter. The quantum-size effects can also give rise to a positive magnetoresistance (inverse spin-valve effect).