Electric and magnetic properties of higher-spin Kondo-Heisenberg models at strong coupling

We study higher-spin (S >= 1) generalization of the one-dimensional Kondo-Heisenberg model, in which the local spin-S moments of the Kondo-lattice model interact with each other via the antiferromagnetic Heisenberg interaction (J(H)), by analytical and numerical methods. The strong-coupling (i.e., large Kondo coupling) expansion maps out an insulating phase at half-filling whose magnetic correlation depends on the parity of 2S as well as a ferromagnetic metallic phase which dominates the strong-coupling region at generic fillings. Then, we carried out the density-matrix renormalization-group simulations for S = 1 to closely investigate the phase structure at large but finite Kondo coupling. At half-filling, the Kondo coupling and J(H) do not compete and the insulating spin-gapless phase is stable, while the competition of the two leads to a stepwise collapse of the strong-coupling ferromagnetism via an intervening dimerized insulating phase with power-law spin correlation at quarter-filling.