Layer Construction of Topological Crystalline Insulator LaSbTe

Topological crystalline insulator (TCI) is one of the symmetry-protected topological states. Any TCI can be looked as a simple product state of several decoupled two-dimensional (2D) topologically nontrivial layers in its lattice respecting its crystalline symmetries, so called layer construction (LC) scheme. In this work, based on first-principles calculations we have revealed that both the tetragonal LaSbTe (t-LaSbTe) and the orthorhombic LaSbTe (o-LaSbTe) can be looked as a stacking of 2D topological insulators in each lattice space. The structural phase transition from t-LaSbTe to o-LaSbTe due to soft phonon modes demonstrates how the real space change can lead to the modification of topological states. Their symmetry-based indicators and topological invariants have been analyzed based on LC. We propose that LaSbTe is an ideal paradigm perfectly demonstrating the LC scheme, which bridges the crystal structures in real space to the band topology in momentum space.