Doping phase diagram of Y1-xCaxBa2(Cu1-yZny)3O7-δ from transport measurements:: Tracking the pseudogap below Tc -: art. no. 054502

The effects of planar hole concentration, p, and magnetic field on the resistivity, p(T), of high-quality c-axis oriented crystalline thin films and sintered Y1-xCaxBa2(Cu1-yZny)(3)O7-delta samples were investigated over a wide range of Ca, Zn, and oxygen contents. Zn was used to suppress superconductivity and this enabled us to extract the characteristic pseudogap temperature, T*(p) below T-c0(p)[equivalent to T-c(x=0,y=0)]. We have also located the characteristic temperature, T-scf, marking the onset of significant superconducting fluctuations above T-c, from the analysis of rho(T,H,p) and rho(T,p) data. From this we are able to identify T*(p) near the optimum doping level where the values of T* (p) and T-scf(p) are very close and hard to distinguish. We again found that T* (p) depends only on the hole concentration p, and not on the level of disorder associated with Zn or Ca substitutions. We conclude that (i) T* (p) (and therefore, the pseudogap) persists below T-c0(p) on the overdoped side and does not merge with the T-c0(p) line and (ii) T* (p) and the pseudogap energy extrapolate to zero at the doping p=0.19 +/- 0.01.