The effects of pressure on the electronic, transport and dynamical properties of AuX₂ (X = Al, Ga and In)

The electronic band structure, transport properties, and lattice dynamics in AuX2 (X = Al, Ga and In) under high pressure have been extensively studied with full potential linearized augmented plane wave and pseudopotential plane wave methods. The theoretical results for the electronic band structure and Fermi surface reveal pressure- induced electronic topological transitions (ETTs) in AuGa2 and AuIn2, while they are absent in AuAl2, in excellent agreement with the experimental observations. Moreover, calculations of the transport properties at different pressures reveal subtle changes in the band structure close to the Fermi surface of the three intermetallic compounds. It is clear that the anomalies in transport properties are due to ETTs. Interestingly, a pressure-induced soft transverse acoustic ( TA) phonon mode is identified only in AuGa2. The TA phonon instability at the Brillouin zone boundary L point might be responsible for the observed first-order phase transition at similar to 8 GPa.