We consider the usual Kondo-lattice, including a Heisenberg-like antiferrom
agnetic exchange between nearest-neighbor localized spins. Using a fermion
representation for the spin operators, we decouple both Kondo and Heisenber
g interactions introducing two mean-held parameters: one associated with th
e local Kondo effect, and the other related to the magnetic correlations be
tween localized spins. We have concentrated on the non-magnetic case. For w
eak Heisenberg coupling, both mean-field parameters are continuously reduce
d as the number of conduction electrons departs from one. When the Heisenbe
rg interaction is strong, magnetic-correlations are almost insensitive to b
and-filling, while the Kondo effect is strongly depleted away from the half
-filled band. (C) 1999 Elsevier Science B.V. All rights reserved.