LOCAL MOMENTS COUPLED TO A STRONGLY CORRELATED ELECTRON CHAIN

A one-dimensional model Hamiltonian that is motivated by the recent di scovery of the heavy-fermion behavior in the cuprates of the Nd2Cu4 ty pe is studied. It consists of t-J interacting conduction electrons cou pled to a lattice of localized spins through a Kondo exchange term J(K ). Exact diagonalization and density matrix renormalization-group meth ods are used. The latter method is generalized to arbitrary densities. At half filling, a spin gap opens for all J(K)>0. Away from half fill ing It is shown that, at strong J(K), the ground state is an unsaturat ed ferromagnet. At weak JK the system is in a paramagnetic phase with enhanced Ruderman-Kittel-Kasuya-Yosida (RKKY) correlations. The import ance of self-screening of the local moments in the depletion regime is discussed. We argue that these findings transcend the specifics of th e model.