Heisenberg antiferromagnet on the square lattice for S>=1

Theoretical predictions of a semiclassical method-the pure-quantum self-consistent harmonic approximation-for the correlation length and staggered susceptibility of the two-dimensional quantum Heisenberg antiferromagnet (2DQHAF) on the square lattice agree very well with recent quantum Monte Carlo data for S=1, as well as with experimental data for the S=5/2 compounds Rb2MnF4 and KFeF4. The theory is parameter free and can be used to estimate the exchange coupling: for KFeF4 we find J= 2.33+/-0.33 meV, consistent with previously determined values. On this basis, the adequacy of the quantum nonlinear a model approach in describing the 2DQHAF when S greater than or equal to 1 is discussed.