GROUND-STATE MAGNETIC-PROPERTIES OF THE KONDO-LATTICE MODEL AT LOW ELECTRON-DENSITIES

The infinite-size version of the density-matrix renormalization-group approach in real space is applied to the Kondo lattice model in one di mension, providing a more accurate determination of the zero-temperatu re magnetic properties for electron densities n less than or equal to 0.5. The paramagnetic state of the free model evolves into a state wit h ferromagnetic correlations, by increasing the strength of the Kondo coupling, in agreement with previous numerical results. The change in the magnetic properties is produced by the competition between the RKK Y mechanism, which favours the paramagnetic state in the weak-coupling region, and the Kondo screening, which leads to the formation of tigh tly bound singlets in the strong-coupling region, enforcing ferromagne tic correlations in the system.