Abstract
We investigated the electron correlation effects in one-dimensional superlattices composed of free (uncorrelated) and repulsive (correlated) sites, using Lanczos diagonalization of chains of up to ten sites described by a Hubbard-like Hamiltonian. The electronic and magnetic properties are shown to depend primarily on the splitting between single-site energies for the correlated and uncorrelated orbitals, respectively, and on the average electron density in the system. The local moments and spin-spin correlations are closely related to the changes in the conductivity, and the magnetic properties are enhanced when the insulating regime is approached. Irrespective of the type of superlattice considered, the local moments form on the correlated orbitals, and may only be induced on single uncorrelated orbitals which separate correlated clusters. The transition from metallic to insulating behaviour can be qualitatively understood in terms of a strongly correlated model, with two Hubbard subbands due to strong Coulomb interactions accompanied by a metallic band of uncorrelated states.
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