Interlayer coupling in magnetic superlattices with electron density inhomogeneities

We discuss the influence of spatial inhomogeneities of the free electron density on the magnetic interaction between magnetic layers of the superlattice, mediated across nonmagnetic, metallic spacer. Using the modified total energy approach, we prove that the TM or RE superlattices the additional scattering of free electrons on magnetic ion multipole moment increases the ferroquadrupolar biquadratic coupling between magnetic layers. It is shown also that the nonuniform free electron density generates contribution to the interlayer coupling being of the Dzialoshinsky-Moriya type.