Intrinsic electronic superconducting phases at 60 K and 90 K in double-layer YBa2Cu3O6+δ

We study superconducting transition temperature (T-c) of oxygen-doped double-layer high-temperature superconductors YBa2Cu3O6+delta (0 <=delta <= 1) as a function of the oxygen dopant concentration (delta) and planar hole-doping concentration (P-pl). We find that T-c, while clearly influenced by the development of the chain ordering as seen in the T-c vs delta plot, lies on a universal curve originating at the critical hole concentration (P-c)=1/16 in the T-c vs P-pl plot. Our analysis suggests that the universal behavior of T-c(P-pl) can be understood in terms of the competition and collaboration of chemical phases and electronic phases that exist in the system. We conclude that the global superconductivity behavior of YBa2Cu3O6+delta as a function of doping is electronically driven and dictated by pristine electronic phases at magic doping numbers that follow the hierarchical order based on P-c, such as 2xP(c), 3xP(c), and 4xP(c). We find that there are at least two intrinsic electronic superconducting phases of T-c=60 K at 2xP(c)=1/8 and T-c=90 K at 3xP(c)=3/16.