Effects of realistic band structures on the interlayer coupling strengths in magnetic multilayers

The interlayer coupling strengths associated with different oscillation periods in Co/Cu/Co sandwiches for different orientations are calculated based on the spin asymmetry of the reflection amplitude at extremal points. A realistic tight-binding model which includes s, ${\mathit{p}}^3$, and ${\mathit{d}}^5$ orbitals is adopted to calculate the reflection amplitudes. At the interface, all evanescent states are included to meet proper boundary conditions. The spin asymmetry of the reflection amplitude which is the crucial factor for determining the coupling strength is found to depend on the details of the band structures. Unique features are found when there are more than one reflected waves, which do not exist in the single-band model. For certain periods inferred from the spacer Fermi surface, the coupling strengths are found too small to be detected.