The study of spin-spin correlations in quasi-one-dimensional Heisenberg antiferromagnetic clusters

For a class of quasi-one-dimensional clusters, by using exact diagonalization, we study the effect of side spins on the spin-spin correlations on the chain. Our calculations show that side spins added in the same sublattice can effectively strengthen the spin-spin correlations in the large-distance region and make the change tend to flatten. It is exactly proved that periodically adding side spins can set up magnetic long-range order in the ground state. We also investigate the effect of the density of side spins on correlation strength. The case where two sublattices have different localized spins is discussed.