Analytical and numerical results for the spectrum of the modified one-dimensional Kondo-lattice model

The ground state and low-lying excitations of the modified one-dimensional Kondo-lattice model for organometallic ferromagnets are studied. Two regions of electron parameters with different types of the model ground state have been found. For the first region the model with one conduction electron per unit cell is reduced to the s=1 antiferromagnetic Heisenberg spin chain. For the second region the ground-state spin S-0 of the model with N unit cells and p conduction electrons has a maximal value if N greater than or equal to p and S-0=\5N-3p\2 if N<p. The detailed analytical and numerical study of the exact one-magnon spectrum of the model with one conduction electron has been presented.