Spin-Peierls groundstates in an electron-lattice periodic Anderson model

Abstract

Novel dimerized antiferromagnetic (homogeneous spin-Peierls) and inhomogeneous-lattice antiferromagnetic (inhomogeneous spin-Peierls) ground states are found in a one-dimensional (1-D) and a two-dimensional (2-D) electron-lattice periodic Anderson model, respectively. Coexistence and mutual enhancement of the Peierls lattice distortion and the antiferromagnetic long-range-order are emphasized. The stoichiometric (half-filling) phase diagrams for the 1-D and 2-D cases are strongly dependent on the hybridization and electron-lattice coupling. For non-stoichiometric fillings, local lattice distortion (coupled spin-charge-lattice small-polaron) states are found: these are discussed in the context of, for example, Ce-based, heavy-fermion systems. Relations to volume collapse phenomena and inorganic spin-Peierls systems, and the similarity of the phase diagrams to those of organic superconductors are also described.