OSCILLATORY MAGNETIC COUPLING BETWEEN METALLIC MULTILAYERS ACROSS SUPERCONDUCTING SPACERS

In order to investigate magnetic coupling between metallic layers acro ss superconducting spacers, we study a simple inhomogeneous free-elect ron model with exchange-split bands in the magnetic region and pairing interaction in the superconducting layers. We solve numerically the c orresponding Bogoliubov-de Gennes equations for spin-dependent potenti als for a one-dimensional geometry and find strong evidence that, whil e the magnetic coupling strength will oscillate as a function of the s pacer layer thickness L, it is strongly damped. This damping can be de scribed by purely exponential form exp(-L/D), where the damping length D is of the order of the coherence length xi(0) of the superconductor . We discuss, briefly, the physical circumstances where such a cut-off of the oscillatory magnetic coupling may be observed.