Interchain Order and Ferromagnetic State in Organic Ferromagnets

Two kinds of alignment of two neighboring organic ferromagnetic chains are studied with Su-Schrieffer-Heeger Hamiltonian added by Hubbard repulsion and antiferromagnetic correlation between side radicals and main chain. The results show that interchain coupling makes the energy gap decreasing. The out-of-phase alignment of two chains is energetically preferred to the in-phase alignment and it is a more possible ferromagnetic structure if the oscillatory part of interchain coupling of the in-phase is small. The spin density and dimerization along the main chain are also discussed.