Scale-free statistics of plasticity-induced surface steps on KCl single   crystals
  Experimental investigations of plastic flow have demonstrated temporal intermittency as deformation proceeds in a series of intermittent bursts with scale-free size distribution. In the present investigation, a corresponding spatial intermittency is demonstrated for plastic flow of KCl single crystals. Deformation bursts lead to large surface steps with a height distribution that is consistent with the distribution of strain increments in deformation of micro-columns, and the energy distribution of acoustic emission bursts observed in deformation of macroscopic single crystal samples of a wide class of materials. 
Jan Schwerdtfeger, Edward Nadgorny, Frederic Madani-Grasset, Vasileios   Koutsos, Jane R. Blackford, Michael Zaiser