Superconductivity without Fe or Ni in the phosphides BaIr2P2 and BaRh2P2

TL;DR

This study reports bulk superconductivity in BaIr2P2 and BaRh2P2, two phosphides with the ThCr2Si2 structure, highlighting the significance of structure and interlayer bonding in superconductivity without Fe or Ni.

Contribution

It demonstrates superconductivity in phosphides with the 122 structure lacking Fe or Ni, emphasizing the role of structure and interlayer P-P bonding in superconductivity.

Findings

Superconductivity confirmed at 2.1K and 1.0K in BaIr2P2 and BaRh2P2.

Structure influences superconductivity, independent of Fe/Ni presence.

Absence of interlayer P-P bonding correlates with superconductivity.

Abstract

Heat capacity, resistivity, and magnetic susceptibility measurements confirm bulk superconductivity in single crystals of BaIr$_2$P$_2$ (T$_c$=2.1K) and BaRh$_2$P$_2$ (T$_c$ = 1.0 K). These compounds form in the ThCr$_2$Si$_2$ (122) structure so they are isostructural to both the Ni and Fe pnictides but not isoelectronic to either of them. This illustrates the importance of structure for the occurrence of superconductivity in the 122 pnictides. Additionally, a comparison between these and other ternary phosphide superconductors suggests that the lack of interlayer $P-P$ bonding favors superconductivity. These stoichiometric and ambient pressure superconductors offer an ideal playground to investigate the role of structure for the mechanism of superconductivity in the absence of magnetism.