The doping phase diagram of Y1-xCaxBa2(Cu1-yZny)3O7-delta from transport measurements: tracking the pseudogap below Tc

TL;DR

This study investigates the pseudogap phase in Y1-xCaxBa2(Cu1-yZny)3O7-delta superconductors by analyzing transport measurements, revealing that the pseudogap persists below Tc and depends solely on hole concentration, not disorder.

Contribution

It provides detailed transport measurements across various doping levels to map the pseudogap phase diagram and clarifies its relationship with superconductivity and disorder effects.

Findings

Pseudogap temperature T* depends only on hole concentration p.

T* persists below the superconducting transition temperature Tc.

T* and pseudogap energy extrapolate to zero at p = 0.19.

Abstract

The effects of planar hole concentration, p, and magnetic field on the resistivity, rho(T), of high-quality c-axis oriented crystalline thin films and sintered Y1-xCaxBa2(Cu1-yZny)3O7-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 Tc0(p) [ = Tc (x =0, y = 0)]. We have also located the characteristic temperature, Tscf, marking the onset of significant superconducting fluctuations above Tc, from the analysis of rho(T,H,p) and rho(T,p) data. This enabled us to identify T*(p) near the optimum doping level where the values of T*(p) and Tscf(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 Tc0(p) on the overdoped side and does not merge with the Tc0(p) line and (ii) T*(p) and the pseudogap energy extrapolate to zero at the doping p = 0.19 +/- 0.01.