Disordered phase of a two-dimensional Heisenberg model with S=1S=1

We use the two-step density-matrix renormalization group method to study an anisotropic version of the J1J1–J2J2 model with S=1S=1. We find a second order transition from a Néel Q=(π,π)Q=(π,π) phase to a disordered phase with a spin gap. This result which is contrasted to our previous finding on S=12 systems suggests the importance of topological effects in the disordered phases of Heisenberg models.