Charge transport of Bi_{2-x}Pb_xSr_2ErCu_2O_8 single crystals near the insulator-superconductor transition

TL;DR

This study investigates how Pb substitution in Bi-based cuprate crystals affects charge transport, revealing increased hole doping, suppressed charge inhomogeneity, and signs of approaching the insulator-superconductor transition.

Contribution

It provides new insights into how Pb doping modulates electronic properties and charge inhomogeneity in Bi-based cuprate superconductors.

Findings

Pb substitution increases hole doping in CuO_2 planes.

Superconducting transition appears near x=0.8 with a resistivity drop at 70 K.

Charge inhomogeneity decreases with higher Pb content.

Abstract

We prepared a set of Pb-substituted Bi_{2-x}Pb_xSr_2ErCu_2O_8 single crystals. The resistivity and the in-plane thermopower decrease with increasing x from 0 to 0.8, which indicates that the Pb substitution supplies holes in the CuO_2 plane. For x=0.8, a tiny resistivity drop (a trace of superconductivity) is seen near 70 K, suggesting that the doping level is close to the critical concentration. The c-axis dielectric constant also systematically changes with x, and suggests that the charge inhomogeneity is suppressed by the Pb substitution.