Superconducting dome and pseudogap endpoint in Bi2201

Once doped away from their parent Mott insulating state, the hole-doped cuprates enter into many varied and exotic phases. The onset temperature of each phase is then plotted versus p—the number of doped holes per copper atom—to form a representative phase diagram. Apart from differences in the absolute temperature scales among the various families, the resultant phase diagrams are strikingly similar. In particular, the p values corresponding to optimal doping (p_opt ∼ 0.16) and to the end of the pseudogap phase (p^∗ ∼ 0.19–0.20) are essentially the same for all cuprate families bar one: the single-layer Bi-based cuprate Bi2+z−yPbySr2−x−zLaxCuO6+δ (Bi2201). This anomaly arises partly due to the complex stoichiometry of this material and also to the different
p values inferred from disparate (e.g., bulk or surface) measurements performed on samples with comparable superconducting transition temperatures Tc. Here, by combining measurements of the in-plane resistivity in zero and high magnetic fields with angle-resolved photoemission spectroscopy studies in the superconducting and normal state, we argue that the phase diagram of Bi2201 may in fact be similar to that realized in other families. This study therefore brings Bi2201 into the fold and supports the notion of universality of p_opt and p^∗ in all hole-doped cuprates.