Cluster Spin Glass Distribution Functions in La$_{2-x}$Sr$_x$CuO$_4$
  Signatures of the cluster spin glass have been found in a variety of experiments, with an effective onset temperature $T_{on}$ that is frequency dependent. We reanalyze the experimental results and find that they are characterized by a distribution of activation energies, with a nonzero glass transition temperature $T_g(x)<T_{on}$. While the distribution of activation energies is the same, the distribution of weights depends on the process. Remarkably, the weights are essentially doping independent. 
R.S. Markiewicz (Northeastern U.), F. Cordero (CNR Roma, Istituto di   Acustica "O.M. Corbino"), A. Paolone, and R. Cantelli...