EFFECT OF SMALL INTERCHAIN COUPLING ON ONE-DIMENSIONAL ANTIFERROMAGNETIC QUANTUM HEISENBERG SPIN SYSTEMS - THE INTEGER-SPIN CASE

A two-dimensional array of weakly coupled antiferromagnetic spin chains is investigated using the Schwinger-boson technique. This method is known to give a good description of integer spins already at the mean-field level. We find that a finite coupling is necessary to introduce long-range antiferromagnetic order, consistently with the presence of a gap for a single chain. The energy gap and spin-spin correlations are calculated. These calculations correspond to the behavior of a nonlinear a model without the one-dimensional topological term.