Superconducting phase diagram of La2$minus;xSrxCuO4 studied using single crystals with Sr-concentration gradient

Abstract We grew single crystals of La 2− x Sr x CuO 4 with Sr-concentration gradient along the crystal growth. Doping dependence of the superconducting transition temperature T c 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.