Pressure-driven tunable properties of the small-gap chalcopyrite topological quantum material ZnGeSb2 : A first-principles study

Search for new topological quantum materials is the demand of time and the theoretical prediction plays a crucial role besides the obvious experimental verification. Divination of topological properties in already well-known narrow gap semiconductors is a flourishing area in quantum material. In this view we revisited the semiconductor compound in the chalcopyrite series, with a very small gap near the Fermi energy. Using the density functional theory-based first-principles calculations, we report a strong topologically nontrivial phase in chalcopyrite ${\mathrm{ZnGeSb}}₂$, which can act as a model system of strained HgTe. The calculations reveal the nonzero topological invariant (${Z}₂$), the presence of Dirac cone crossing in the surface spectral functions with spin-momentum locked spin texture. We also study the interplay between the structural parameters and electronic properties, and report the tunable topological properties due to a very small band gap, from nontrivial to trivial phase under the application of moderate hydrostatic pressure within $\ensuremath{\approx}7$ GPa. A small modification of a lattice parameter is enough to achieve this topological phase transition which is easily accomplished in an experimental laboratory. The calculations show that a discontinuity in the tetragonal distortion of noncentrosymmetric ${\mathrm{ZnGeSb}}₂$ plays a crucial role in driving this topological phase transition. Our results are further collaborated with a low energy $\mathbf{k}\ifmmode\cdot\else\textperiodcentered\fi{}\mathbf{p}$ model Hamiltonian to validate our $\mathit{ab}\mathit{initio}$ findings. We showed that the evaluation of the model band energy dispersion under the hydrostatic pressure is consistent with the obtained results.