Two Superconducting Transitions in Single Crystal   La$_{2-x}$Ba$_x$CuO$_4$
  We use spatially-resolved transport techniques to investigate the superconducting properties of single crystals La$_{2-x}$Ba$_x$CuO$_4$. We find a new superconducting transition temperature $T_{cs}$ associated with the ab-plane surface region which is considerably higher than the bulk $T_c$. The effect is pronounced in the region of charge carrier doping $x$ with strong spin-charge stripe correlations, reaching $T_{cs}=36$ K or 1.64$T_c$. 
X. Y. Tee, T. Ito, T. Ushiyama, Y. Tomioka, I. Martin, C. Panagopoulos
cond-mat.supr-con