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

Abstract

Honeycomb structure has frequently been observed in two-dimensional (2D) materials. CuAu in the buckled honeycomb (BHC) structure was synthesized recently, which is a case of a 2D intermetallic compound. Here, the dynamical stability of 2D $AX$ in the BHC structure, where $A=\mathrm{Cu}$, 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 $AX$, 48 $AX$ are identified to be dynamically stable. In addition, we discuss (i) the relationship between the dynamical stability and the formation energy, (ii) a correlation of the dynamical stability between different constituents $A$, and (iii) trends of the structural, elastic, electronic, and magnetic properties. Furthermore, a stable phase of the B11-type AuZr is predicted based on both the result (ii) and the stability relationship between 2D and 3D structures. The stability of B11 AuZr is consistent with other predictions using the machine learning approach. The present findings should stimulate future studies exploring the physics and chemistry of 2D intermetallic compounds.