Structural, stability and electronic properties of A7 SbAs rhombohedral phase under pressure variations

Abstract

Antimony arsenide (SbAs), a bulk 3D binary compound has attracted significant interest since its experimental discovery in 2013. This is due to its potential applications in fields such as electronics, topological insulators, optoelectronics, thermoelectrics, and piezoelectrics. In the A7 rhombohedral phase, SbAs manifests a pseudo-layered structure with interlayer interactions mediated by weak van der Waals forces. In the present work, we have employed first-principles calculations to investigate the pressure-dependent structural, stability, and electronic properties of SbAs in the A7 phase. Our results indicate that the lattice parameter along the a-axis shows a continuous reduction under pressure, whereas, the c-axis evolves with anisotropic compression. Bond lengths and bond angles decrease systematically with a linear trend emerging above 60 GPa like the lattice parameters. Symmetry analysis shows a pressure-induced phase transition from the non-centrosymmetric space group R3m to the centrosymmetric Rm. Phonon dispersion relations show a lack of imaginary modes at ambient pressure, but the onset of instability is observed between 20 and 40 GPa, with the appearance of imaginary modes that decrease in intensity from the former to the latter stated pressure point. However, these modes dissipate from around 60 GPa and above signifying the material's dynamic stability at high pressures. On the electronic front, SbAs exhibits a transition from a semimetallic to a metallic state with increasing pressure accompanied by a rise in the Fermi energy. Furthermore, spin-orbit coupling (SOC) has also been observed to play a significant role in the material's electronic characteristics.