THE EFFECT OF INTERCHAIN COUPLING ON ENERGY-BANDS AND FERROMAGNETIC ORDER IN QUASI-ONE-DIMENSIONAL ORGANIC POLYMER FERROMAGNETS

Considering the interchain interaction as an interchain electron trans fer, a theoretical model is developed to describe quasi-one-dimensiona l organic ferromagnets. We also take into account the interaction betw een the itinerant pi electrons and the distortion of the lattice, the Hubbard electron-electron repulsion, and the antiferromagnetic correla tion between the pi electrons and the nonbonding electrons at the site radicals. By employing the mean-field approximation, four energy band s which exhibit a three-dimensional anisotropic aspect are obtained. W hen the interchain coupling increases, the energy gap decreases. In th e case of small dimerization order parameter, due to the interchain co upling, the band gap may disappear and the conjugated pi electrons in the main chain show ferromagnetic order in the ground state. The inter chain coupling destabilizes the ferromagnetic ground state of the syst em.