Topological states of Sr3PbO: From topological crystalline insulator phase in the bulk to quantum spin Hall insulator phase in the thin-film limit

Nontrivial topological materials are emerging as fascinating objects in condensed matter research due to their great potential in low-power and low-dissipation electronic applications. In this work, using first-principles calculations and a tight-binding method, we propose a promising candidate with novel topological states and high experimental feasibility. We prove that Sr3PbO exhibits a topological crystalline insulator (TCI) phase in its three-dimensional (3D) bulk lattice and a quantum spin Hall insulator (QSHI) phase in its two-dimensional (2D) thin film, presenting a picture of evolution from 3D TCI to 2D QSHI. Moreover, the topological phase transition between QSHI and trivial phases occurs as the thickness of the thin-film Sr3PbO varies. This intriguing behavior can also be confirmed using a low-energy effective model with infinite potential well boundary conditions. The high-quality bulk and thin-film Sr3PbO have been prepared in an experiment, implying high feasibility for experimental characterization.