Pressure-induced topological phase transition in Lu2S3 system

Pressure is a powerful tool for tuning properties of materials, capable of inducing high- superconductivity, topological phase transition and other novel states. Here, we systematically investigate the pressure-induced topological phase transition in the Lu 2 S 3 system. Both the predicted P4/mbm phase (from 9 GPa to 57 GPa) and the I4/mmm phase (from 57 GPa to 200 GPa) feature cage-like structure, with Lu atoms centered within S polyhedra. Without spin-orbit coupling (SOC), the orbital-resolved band structures reveal band inversion between Lu- and S- dominated states, giving rise to a nodal square in the P4/mbm phase and a nodal crown in the I4/mmm phase. Once including SOC, the nodal square and nodal crown are fully gapped, leading to the strong topological insulator phase and weak topological insulator phase in the P4/mbm and I4/mmm phase, respectively. Furthermore, we explore the evolutions of these topological phases under various perturbations, indicating that they can serve as parent compounds for diverse topological states, including Dirac points, composite nodal lines and topological insulators. Our results reveal the rich topological physics in the Lu 2 S 3 system under pressure and provide guidance for future experimental studies and potential electronic applications.