MAGNETIC-SUBLAYERS EFFECT ON THE EXCHANGE-COUPLING OSCILLATIONS VERSUS CAP-LAYER THICKNESS

We have found that some periods of interlayer exchange coupling (IEC) oscillations as a function of cap-layer (CL) thickness may be suppressed if the in-plane extremal spanning vectors of the cap- and ferromagnet-materials Fermi surfaces do not coincide. The suppression of the IEC oscillations vs. the CL thickness holds also if the magnetic slab thickness tends to infinity. On the one hand, we have shown by means of very simple arguments that apart from the well-known selection rules concerning the spacer- and cap-layers, another one related with the magnetic sublayers has to be fulfilled in order that the interlayer coupling oscillations $vs.$ CL thickness could survive. On the other hand, the distribution of induced magnetic moments across the non-magnetic cap- and spacer-sublayers have been computed and shown to reveal the underlying periodicity of the materials they are made of (i.e. related to their bulk Fermi surfaces) independently of whether or not the selection rules are fulfilled. This means that the IEC oscillations are of global nature and depend on all the sublayers the system consists of.