INTERCHAIN COUPLING MODEL FOR QUASI-ONE-DIMENSIONAL PI-CONJUGATED ORGANIC FERROMAGNETS

Two neighboring pi-conjugated organic-polymer ferromagnetic chains are described individually by a Hamiltonian, which is the Su-Schrieffer-H eeger Hamiltonian added by the Hubbard electron-electron repulsion. In consideration of the topological structure of the system, the interch ain coupling is taken into account as an interchain electron-transfer term, which is different with respect to different sites in chains. Th e splitting of energy levels with respect to different chains, the fer romagnetic order, and the dimerization are studied in detail. It is sh own that in the high-spin ground state of the system, different config urations with interchain coupling will result in transfer of spin dens ity between the main chain and side radical, and appropriate coupling strength stabilizes the high-spin ground state. However, as the coupli ng reaches a critical value, the energy gap disappears and the high-sp in state does not exist. It is also found that the dimerization along the main chain varies with the interchain coupling.