Exact asymptotic behavior of correlation functions for disordered   spin-1/2 XXZ chains
  We consider an XXZ spin-1/2 chain in the presence of several types of disorder that do not break the XY symmetry of the system. We calculate the complete asymptotic form of the spin-correlation functions at zero temperature at the transition between liquid and disordered phase that occurs for a special value of anisotropy in the limit of small disorder. Apart from a universal power law decay of correlations, we find additional logarithmic corrections due to marginally irrelevant operator of disorder. 
Zoran Ristivojevic, Aleksandra Petkovic, and Thierry Giamarchi
cond-mat.stat-mech cond-mat.dis-nn quant-ph