Ag-Au alloys BCS-like Superconductors?

TL;DR

This study uses first principles calculations to predict superconductivity in Ag-Au alloys and related compounds, finding very low transition temperatures in bulk and 2D forms, with some known and new compounds exhibiting superconductivity.

Contribution

It is the first to predict superconductivity in Ag-Au alloys and related compounds using first principles methods, including new potential superconductors.

Findings

Ag-Au alloys have Tc as low as 1 mK.

Known superconducting compounds like Au2Bi and Nb3Au have Tc of 3.6 K and 10.1 K.

New predicted superconductors Ag2Bi and Nb3Ag have Tc of 6.1 K and 10.8 K.

Abstract

Prompted by the recent report on the evidence for superconductivity at ambient temperature and pressure in nanostructures of silver particles embedded into a gold matrix [arXiv:1807.08572], we have exploited first principles materials discovery approaches to predict superconductivity in the 3D bulk crystals and 2D slabs of Ag-Au binary alloys at 1 atm pressure within the phonon-mediated BCS-like pairing mechanism. In calculations, it turns out that, the estimated superconducting transition temperatures of the ensued stable and metastable Ag-Au alloys resulted in Tc as low as one mK. Whereas similar calculations for the known superconducting intermetallic compounds consisting of gold, Laves Au2Bi and A15 Nb3Au predict Tc =3.6 K and 10.1 K, respectively, corroborate with experiments. And, the hitherto unknown silver analogues, Ag2Bi and Nb3Ag are also found to be superconducting at 6.1 K and 10.8 K, respectively. Furthermore, we show that, elemental Au in its metastable 9R, and hcp phases superconduct at Tc =1 mK; but not Ag, in these hexagonal lattices.