Temperature dependent correlation length for the S=1/2 Quantum Heisenberg Antiferromagnet on the square lattice

Abstract

We present an analysis of high precision Monte Carlo data for the two dimensional S=1/2 quantum Heisenberg antiferromagnet up to $\xi =95.7(3)$ obtained by the continuous time version of the loop algorithm. Our data are in good agreement with a prediction of the recent theory (Phys. Rev. Lett. vol. 77, 3439 (1996)) in very high temperature regime, but they strongly disagree with it in the low temperature regime.

Comments: Modified with improved data; to appear in Phys. Rev. Lett. as a Comment; latex file and one eps file