Magnetism in one-dimensional Hubbard superlattices

We consider fermions in one-dimensional superlattices (SL's), modeled by si te-dependent Hubbard-U couplings arranged in a repeated pattern of repulsiv e (i.e., U > 0) and free (U = 0) sites. Lanczos diagonalization is used to investigate magnetic properties. For each SL configuration, we found that l ocal moments are displaced from repulsive to fi ee sites as the density is reduced and we were able to establish three distinct regions in a "phase di agram." We also determined that spin density waves can be frustrated or res tored upon doping with either electrons or holes. A connection between the spacer thickness dependence of the maxima in the magnetic structure factor and the oscillation of the exchange coupling in magnetic multilayers was al so established.