  We investigate the influence of the carrier density and other parameters on
the interlayer exchange in magnetic thin film systems. The system consists of
ferromagnetic and non-magnetic layers where the carriers are allowed to move
from layer to layer. For the ferromagnetic layers we use the Kondo-lattice
model to describe interactions between itinerant electrons and local moments.
The electrons' properties are calculated by a Green's function's equation of
motion approach while the magnetization of the local moments is determined by a
minimization of the free energy. As results we present magnetic phase diagrams
and the interlayer exchange over a broad parameter range. Additionally we can
calculate the transition temperatures for different alignments of the
ferromagnetic layers' magnetizations.
