Superconductivity in Nb5Ir3-xPtxO

TL;DR

This study explores how substituting Pt for Ir in Nb5Ir3-xPtxO affects its superconducting transition temperature, revealing complex dependencies beyond simple lattice parameter changes and comparing it with other two-gap superconductors.

Contribution

It provides new insights into the relationship between composition, structure, and superconductivity in Nb5Ir3-xPtxO, highlighting non-linear Tc behavior and its comparison with other two-gap superconductors.

Findings

Nb5Ir3O has Tc of 10.5 K, Nb5Pt3O has Tc of 3.8 K

Tc varies non-linearly with Pt substitution, not solely determined by lattice parameters

Comparison with MgB2, Mo8Ga41, Nb3Sn suggests complex superconducting mechanisms

Abstract

We have investigated the superconducting critical temperature Tc of solid solution Nb5Ir3-xPtxO with the Ti5Ga4-type structure. The both end-members of Nb5Ir3O and Nb5Pt3O are reported to be superconductors with Tc of 10.5 K and 3.8 K, respectively. Particularly Nb5Ir3O is considered as a two-gap superconductor. The entire series of alloy hold the Ti5Ga4-type structure and show the linear x dependence of lattice parameters. On the other hand, a nonlinear Tc vs x plot was obtained, suggesting that Tc is not determined by only lattice parameters. The experimental result is discussed based on the Matthias rule and compared with those of the other two-gap superconductors such as MgB2, Mo8Ga41 and Nb3Sn.