The correlation length of the Heisenberg antiferromagnet with arbitrary spin S

Experiments and numerical data on the correlation length for large S disagree strongly with the theoretical prediction based on the effective field theory prescription of the magnon physics. The reason is that for large S, at any accessible correlation lengths, the cut-off effects from the non-magnon scales become large and can not be treated by an effective field theory. We study these effects in a spin-wave expansion. The corrected prediction connects the renormalized classical and the classical scaling regions smoothly and comes close to the data.