High-pressure study of the aurophilic topological Dirac material AuI
Jaspreet Singh, Sushree Sarita Sahoo, Kanchana Venkatakrishnan, G. Vaitheeswaran, Daniel Errandonea
Abstract
We endeavour to explore the high-pressure study in the aurophilic AuI within the state-of-the-art of first principles. The impediment of expressing precise ground-state features of aurophilic compounds that had afflicted prior theoretical research has been resolved by incorporating van der Waals corrections (vdw). Mechanical and dynamical stability are ensured at ambient using the computed elastic constants and phonon dispersion curves. The dynamical instability is triggered by the application of pressure in AuI, as evidenced by the softening of an acoustic mode (Eu) at ∼7 GPa. Non-adherence of estimated elastic constants to the Born stability criterion at this pressure illustrates the system's mechanical instability. As previously demonstrated in experiments, the pressure-driven amorphization is rationalised by the phonon softening and elastic instability. Our calculations of the electronic band structure reveal an indirect bandgap (2.31 eV). Z2 invariants confirm that non-symmorphic AuI is a non-trivial Dirac material with the inclusion of spin-orbit coupling. Furthermore, a type-A hourglass dispersion with movable Dirac point is observed at the two-fold screw rotation axis (C2y). The pressure-dependent electronic structure reveal that the band topology is unaffected by pressure up to amorphous state. Our findings predict that this aurophilic class of material AuI possess exotic structural and electronic properties, encouraging further studies.