A STUDY ON THE GROUND-STATE IN INTERCHAIN COUPLED QUASI-ONE-DIMENSIONAL ORGANIC FERROMAGNETS

We deal with two neighbouring pi-conjugated organic ferromagnetic chai ns with a Hamiltonian including the Hubbard on-site electron-electron repulsion and nearest-neighbouring Coulomb repulsion. We take into acc ount the interchain coupling as an interchain electron-transfer term, which is different with respect to different sites in chains. The dist ribution of charge density, the ferromagnetic order and the stability of the high-spin ground state are studied in detail. It is shown that the nearest-neighbouring Coulomb repulsion leads to inhomogeneous dist ribution of charge density and spin density with respect to different sites. The interchain coupling results in transfers of charge density and spin density between the main chain and the side radicals. The int erchain coupling stabilizes the high-spin ground state while the neare st-neighbouring Coulomb repulsion makes it unstable.