# Structural transition in AuAgTe4 under pressure

## TL;DR

This study predicts a pressure-induced structural transition in AuAgTe4 at around 5 GPa, transforming it from a bad metal to a typical metal and potentially inducing superconductivity, similar to related compounds.

## Contribution

First theoretical prediction of a pressure-driven structural transition and metallization in AuAgTe4, suggesting possible superconductivity at high pressure.

## Key findings

- Structural transition at ~5 GPa with regularized Te6 octahedra.
- Disappearance of Te-Te dimers at high pressure.
- Transition from bad metal to typical metal with Te 5p states.

## Abstract

Gold is inert and forms very few compounds. One of the most interesting of those is calaverite AuTe2, which has incommensurate structure and which becomes superconducting when doped or under pressure. There exist a "sibling" of AuTe2 the mineral sylvanite AuAgTe4, which properties are almost unknown. In sylvanite Au and Ag ions are ordered in stripes, and Te6 octahedra around metals are distorted in such a way that Ag becomes linearly coordinated, what is typical for Ag^{1+}, whereas Au is square coordinated - it is typical for d^8 configurations, i.e. one can assign to Au the valence 3+. Our theoretical study shows that at pressure P_C ~ 5 GPa there should occur in it a structural transition such that above this critical pressure Te6 octahedra around Au and Ag become regular and practically identical. Simultaneously Te-Te dimers, existing at P = 0 GPa, disappear, and material from a bad metal becomes a usual metal with predominantly Te 5p states at the Fermi energy. We expect that, similar to AuTe2, AuAgTe4 should become superconducting above P_C.