Revised phase diagram of the high-$T_c$ cuprate superconductor Pb-doped Bi$_2$Sr$_2$CaCu$_2$O$_{8+δ}$ revealed by anisotropic transport measurements

Abstract

The phase diagram of high transition temperature (high-T c ) cuprates is elucidated via systematic anisotropic transport measurements for Pb-doped Bi-2212 single crystals. We demonstrate that the onset temperatures of the "weak" pseudogap and electronic coherence cross each other at a critical doping level, while the onset of the "strong" pseudogap merges into that of superconducting fluctuations above the critical doping level. These results indicate the importance of Mottness in high-T c superconductivity.