Superconducting phase diagram of La2−xSrxCuO4 studied using single crystals with Sr-concentration gradient

We grew single crystals of La2−xSrxCuO4 with Sr-concentration gradient along the crystal growth. Doping dependence of the superconducting transition temperature Tc was determined by magnetic susceptibility measurement at different positions of the crystal. The results revealed a dramatic degradation of superconductivity at around x∼0.12 more clearly compared to the previously determined phase diagram using powder samples or single crystals with uniform Sr-concentration.