A Family of Pb-based Superconductors with Variable Cubic to Hexagonal Packing

TL;DR

This paper reports the discovery of three new Pb-based superconductors with variable crystal structures, expanding understanding of how stacking variations influence superconductivity in intermetallic compounds.

Contribution

The study introduces three previously unreported Pb-based superconductors with variable stacking structures and confirms their superconducting properties, highlighting the minor role of stacking variation.

Findings

Superconducting transition temperatures around 2-2.7 K.

Materials are moderate coupling superconductors.

Pb stacking variation has limited impact on superconductivity.

Abstract

We describe three previously unreported superconductors, BaPb3, Ba0.89Sr0.11Pb3 and Ba0.5Sr0.5Pb3. These three materials, together with SrPb3, form a distinctive isoelectronic family of intermetallic superconductors based on the stacking of Pb planes, with crystal structures that display a hexagonal to cubic perovskite-like progression, as rarely seen in metals. The superconducting transition temperatures (Tc) are similar for all - 2.2 K for BaPb3, 2.7 K for Ba0.89Sr0.11Pb3 and 2.6 K for Ba0.5Sr0.5Pb3, and the previously reported Tc of SrPb3, ~ 2 K, is confirmed. The materials are moderate coupling superconductors, and calculations show that the electronic densities of states at the Fermi energy are primarily contributed by Pb. The observations suggest that the Pb-stacking variation has only a minor effect on the superconductivity.