Interrelations among critical current density, irreversibility field and pseudogap in hole doped high-Tc cuprates

TL;DR

This study investigates how hole doping and oxygen deficiency influence the critical current density and irreversibility field in high-Tc cuprates, revealing that carrier concentration primarily governs these properties through the pseudogap.

Contribution

It demonstrates that intrinsic critical current density and irreversibility field are mainly determined by hole concentration and pseudogap effects, with oxygen disorder playing a secondary role.

Findings

Maximum Jc0 at p ~ 0.185 independent of oxygen deficiency

H0 and Jc0 show similar p-dependence linked to the pseudogap

Critical current density correlates with the superconducting condensation energy

Abstract

The effects of hole content (p) and oxygen deficiency (delta) on the zero-field critical current density, Jc0, were investigated for high-quality c-axis oriented Y1-xCaxBa2Cu3O7-delta (x = 0, 0.05, 0.10, and 0.20) thin films. Low temperature critical current density of these films above the optimum doping were found to be high and were primarily determined by the hole concentration, reaching a maximum at p ~ 0.185 +/- 0.005, irrespective of the level of oxygen deficiency. This implies that oxygen disorder plays only a secondary role and the intrinsic Jc0 is primarily governed by the carrier concentration in the copper oxide planes. Further support in favor of this was found from the analysis of the in-plane resistive transitions of c-axis oriented crystalline thin films of YBa2Cu3O7-delta (YBCO) under magnetic fields (H) applied along the c-direction, over a wide range of doped holes. The characteristic magnetic field (H0), linked to the vortex activation energy and the irreversibility field, exhibits similar p-dependence as shown by Jc0(p). We have explained these observations in terms of the doping dependent pseudogap (PG) in the low-energy electronic energy density of states. Both the intrinsic critical current density and the irreversibility field depend directly on the superconducting condensation energy, which in turn is largely controlled by the magnitude of the hole concentration dependent PG in the quasiparticle spectral density.