Ferromagnetism, dimerization, charge and spin density waves in quasi-one-dimensional organic polymers: Self-consistent mean field theory

Abstract

We address the low temperature properties of quasi-one-dimensional organic polymers, which may be described by a modified Anderson lattice-Su-Schrieffer-Heeger Hamiltonian. The condition and nature of various orders, such as, the ferromagnetic order, the dimerization order, the charge density wave order and the spin density wave order, are analyzed by a self-consistent mean field theory. Analytical results are obtained for a specific case. The topological structure of the chain leads to a flatband structure of the energy band, which gives rise to a ferromagnetic order in the case of half filling at low temperatures. The on-site Coulomb repulsion enhances the ferromagnetic order, while the nearest-neighbor interaction (V) suppresses both the ferromagnetic order and the dimerization, and leads to the charge density wave. The π-d hybridization (t d) suppresses the dimerization, and does not affect the magnetization. The ferromagnetic order and dimerization order coexist for weak t d.