Phase diagram of the one-dimensional Kondo-lattice model

The phase diagram of the one-dimensional Kondo lattice is determined by numerical diagonalization of both the original and an effective Hamiltonian describing the strong-coupling limit. The ground state in the strong-coupling region is ferromagnetic for all electron concentrations away from half filling. The weak-coupling region is characterized by a paramagnetic Luttinger liquid. For the finite-size systems studied here, the dominant spin and charge correlations are at 2${\mathit{k}}_{\mathit{F}}$ of the conduction band.