Temperature dependent spatial oscillations in the correlations of the   XXZ spin chain
  We study the correlation $<\sigma^z_0\sigma^z_n>$ for the XXZ chain in the massless attractive (ferromagnetic) region at positive temperatures by means of a numerical study of the quantum transfer matrix. We find that there is a range of temperature where the behavior of the correlation for large separations is oscillatory with an incommensurate period which depends on temperature. 
Klaus Fabricius, Andreas Kl\"umper and Barry M. McCoy