An RKKY-induced dimerized phase of the Kondo lattice model

We clarify the nature of the dimerized ground state found in the one-dimensional Kondo lattice model at quarter conduction electron filling. The conduction electrons mediate, through the RKKY mechanism, the long-range interactions among localized spins necessary to induce dimerization in that sub-system. On the other hand, the feedback of the local moments on the conduction electron fluid does not induce dimerization in the latter, whose spin sector remains gapless. The same feedback, however, is able to open a charge gap