PHASE-DIAGRAM OF THE KONDO-LATTICE MODEL

The Kondo lattice model can be characterized by two parameters: one is the exchange coupling constant J/t and the other is the density of conduction electrons rho = N/L. In the low-density limit the Kondo lattice model has a ferromagnetic ground state for any J. In one dimension one can show further that the ground state is ferromagnetic also in the strong coupling limit at any rho, while it has a spin liquid ground state at the half-filling. The phase diagram of the Kondo lattice model in one dimension is discussed in the entire space of the parameters based on exact diagonalization.