Spin-Peierls ground states in an electron-lattice periodic Anderson model

Novel dimerized antiferromagnetic (homogeneous spin-Peierls) and inhomogene ous-lattice antiferromagnetic (inhomogeneous spin-Peierls) ground states ar e found in a one-dimensional (I-D) and a two-dimensional (2-D) electron-lat tice periodic Anderson model, respectively. Coexistence and mutual enhancem ent of the Peierls lattice distortion and the anti-ferromagnetic long-range -order are emphasized. The stoichiometric (half-filling) phase diagrams for the I-D and 2-D cases are strongly dependent on the hybridization and elec tron-lattice coupling. For non-stoichiometric fillings, local lattice disto rtion (coupled spin-charge-lattice small-polaron) states are found: these a re discussed in the context of, for example, Ce-based, heavy-fermion system s. Relations to volume collapse phenomena and inorganic spin-Peierls system s, and the similarity of the phase diagrams to those of organic superconduc tors are also described.