Charge ordering due to π–dπ–d coupling in one-dimensional system

We investigate the one-dimensional extended Hubbard model at quarter filling coupled to antiferromagnetically ordered Ising spins to elucidate the interplay between ππ correlated electrons and d localized spins in π–dπ–d systems. Temperature dependence of charge and spin correlations are calculated by quantum Monte Carlo simulations. The results show that the coupling to the Ising spins remarkably enhances charge-order correlation in the presence of the intersite Coulomb repulsion and furthermore induces ferromagnetic correlation. We also discuss our results in connection with recent experiments on the Fe-phthalocyanine compound TPP[Fe(Pc)(CN)2]2TPP[Fe(Pc)(CN)2]2.