Superconductor-Insulator Phase Separation Induced by Rapid Cooling in   kappa-(ET)_2Cu[N(CN)_2]Br
  We present measurements of the low temperature specific heat of single crystals of kappa-(ET)_2Cu[N(CN)_2]Br as a function of the cooling rate through the glasslike structure transition at $\sim$ 80K. We find that rapid cooling produces a small (< 4%) decrease in the superconducting transition temperature accompanied by a substantial (up to 50%) decrease in the normal-state electronic specific heat. A natural explanation of our data is that there is a macroscopic phase separation between superconducting and insulating regions in rapidly cooled samples. 
O.J. Taylor, A. Carrington, and J.A. Schlueter