Old puzzle of incommensurate crystal structure of calaverite AuTe$_2$ and predicted stability of novel AuTe compound

TL;DR

This paper resolves the longstanding incommensurate structure puzzle of AuTe₂ by showing charge redistribution on Te sites and predicts a new stable AuTe compound with potential superconductivity.

Contribution

It introduces a charge-transfer perspective to explain AuTe₂'s structure and predicts a novel stable AuTe compound based on computational modeling.

Findings

Charge redistribution occurs mainly on Te sites in AuTe₂.

The incommensurate structure reduces Coulomb energy costs.

Predicted a new stable AuTe compound with a specific crystal structure.

Abstract

It is shown that the long-standing puzzle of incommensurate crystal structure of AuTe$_2$ can be solved, if this material is considered as a negative charge-transfer system. Using modern computational methods, we demonstrate that charge redistribution associated with incommensurate modulations of crystal structure occurs not so much on Au, but predominantly on Te sites. This substantially reduces Coulomb energy costs for creating such a unique crystal structure. The same mechanism also explains superconductivity of doped AuTe$_2$. Exploring different Au-Te compositions, we also discovered a previously unknown compound AuTe, which theoretically is very stable, and we predict its crystal structure.