Effect of chemical inhomogeneity in the bismuth-based copper oxide superconductors

TL;DR

This study investigates how chemical inhomogeneity, specifically cation disorder at the Sr site, impacts the superconducting transition temperature in bismuth-based copper oxide superconductors, revealing ways to enhance Tc.

Contribution

It demonstrates that reducing Sr site disorder can significantly increase Tc in Bi2212, providing insights into chemical inhomogeneity effects in high-temperature superconductors.

Findings

Tc decreases monotonically with ionic radius mismatch in Sr site substitutions.

Minimizing Sr site disorder increases Tc in Bi2212 to 96 K.

Chemical inhomogeneity affects superconducting properties in bulk high-Tc materials.

Abstract

We examine the effect on the superconducting transition temperature (Tc) of chemical inhomogeneities in Bi2201 and Bi2212 single crystals. Cation disorder at the Sr crystallographic site is inherent in these materials and strongly affects the value of Tc. Partial substitution of Sr by Ln (Ln = La, Pr, Nd, Sm, Eu, Gd, and Bi) in Bi_{2}Sr_{1.6}Ln_{0.4}CuO_{6} results in a monotonic decrease of Tc with increasing ionic radius mismatch. By minimizing Sr site disorder at the expense of Ca site disorder, we demonstrate that the Tc of Bi2212 can be increased to 96 K. Based on these results we discuss the effects of chemical inhomogeneity in other bulk high-temperature superconductors.