Silvanite AuAgTe$_4$: a rare case of gold superconducting material

• DOI: 10.48550/arxiv.2301.08033
• Publication Date: 2023-01-01
• Authors: Y. Amiel; Gyanu P. Kafle; Evgenia V. Komleva; Eran Greenberg; Yu. S. Ponosov; Stella Chariton; Barbara Lavina; Dongzhou Zhang; A. Palevski; A. V. Ushakov; D. I. Khomskiǐ; I. I. Mazin; S. V. Streltsov; Elena R. Margine; G. Kh. Rozenberg
• Keywords: Monoclinic crystal system

Gold is one of the most inert metals, forming very few compounds, some with rather interesting properties, and only two them currently known to be superconducting under certain conditions (AuTe$_2$ SrAuSi$_3$). Compounds another noble element, Ag, are also relatively rare, superconducting. Finding new materials containing gold (and silver) a challenge - especially having in mind that best high-$T_c$ superconductors at normal based upon their close ''relative'', Cu. Here we report combined X-ray diffraction, Raman, resistivity measurements, as well first-principles calculations, explore effect hydrostatic pressure on properties sylvanite mineral, AuAgTe$_4$. Our experimental results, supported by density functional theory, reveal structural phase transition $\sim$5 GPa from monoclinic $P2/c$ $P2/m$ phase, resulting almost identical coordinations Au Ag ions, uniform interatomic distances. Further, measurements show onset superconductivity $\sim$1.5 followed linear increase $T_c$ up transition, maximum gradual decrease afterwards. calculations indicate phonon-mediated superconductivity, electron-phonon coupling coming predominantly low-energy phonon modes. Thus, along discovery compound gold/silver, our results advance understanding mechanism Au-containing which may pave way novel ones.