  We develop an interpolating self-energy approach to the correlated
Kondo-lattice model. The correlation of the band electrons is taken into
account by a Hubbard interaction. The method is based on a self-energy ansatz,
the structure of which allows to fulfill a maximum number of exactly solvable
limiting cases. The parameters of the ansatz are fitted to spectral moments via
high-energy expansion of the self-energy. The band electron correlations are
taken into account by an effective medium approach being correct in the strong
coupling (U) regime. The theory is considered reliable for all temperatures,
band occupations, and exchange couplings. Results are presented for the
respective dependencies of spectral densities, quasiparticle densities of
states, and characteristic correlation functions, and interpreted in terms of
elementary spin exchange processes between itinerant conduction electrons and
localized magnetic moments. The appearance of magnetic polarons, the typical
quasiparticle of Kondo-lattices, in the energy spectrum is worked out. Spin
exchange processes prevent a total spin polarization of the band electrons even
for arbitrarily strong exchange couplings as long as the local moments are
represented by quantum mechanical spins.
