Comprehensive search for buckled honeycomb binary compounds based on noble metals (Cu, Ag, and Au)

TL;DR

This study systematically investigates the dynamical stability of buckled honeycomb 2D intermetallic compounds with noble metals, identifying over 50 stable structures and predicting a new stable phase of AuZr, thus advancing 2D materials research.

Contribution

It provides a comprehensive first-principles analysis of stability, electronic, and magnetic properties of 2D $AX$ compounds with noble metals, and predicts a new stable phase of AuZr.

Findings

Over 50 stable 2D $AX$ compounds identified.

Correlation between stability and formation energy established.

Prediction of a new stable AuZr phase.

Abstract

Honeycomb structure has been frequently observed in two-dimensional (2D) materials. CuAu in the buckled honeycomb (BHC) structure has been synthesized recently, which is the first case of 2D intermetallic compounds. Here, the dynamical stability of 2D $AX$ in the BHC structure, where $A=$ Cu, Ag, and Au and $X$ is a metallic element in the periodic table, is systematically studied by calculating phonon dispersions from first-principles. Among 135 $AX$, more than 50 $AX$ are identified to be dynamically stable. In addition, (i) a relationship between the dynamical stability and the formation energy, (ii) a correlation of dynamical stability between different constituents $A$, (iii) a trend of lattice parameters, and (iv) electronic and magnetic properties are discussed. Furthermore, a stable phase of B11-type AuZr is predicted based on both the result (ii) and the stability relationship between 2D and three-dimensional structures. The present findings stimulate future studies exploring physics and chemistry of 2D intermetallic compounds.