Layer Construction of Topological Crystalline Insulator LaSbTe

TL;DR

This paper uses first-principles calculations to show that LaSbTe exists as layered 2D topological insulators, illustrating the layer construction paradigm that links real-space structure to momentum-space topology.

Contribution

It demonstrates that LaSbTe compounds can be understood as stacking 2D topological insulators, providing a concrete example of the layer construction approach for topological crystalline insulators.

Findings

LaSbTe can be viewed as stacking 2D topological insulators.

Structural phase transition affects topological states.

LaSbTe exemplifies the layer construction paradigm.

Abstract

Topological crystalline insulator (TCI) is one of the symmetry-protected topological states. Any TCI can be deformed into a simple product state of several decoupled two-dimensional (2D) topologically nontrivial layers in its lattice respecting its crystalline symmetries called the layer construction (LC) limit. In this work, based on first-principles calculations we have revealed that both tetragonal LaSbTe (t-LaSbTe) and orthorhombic LaSbTe (o-LaSbTe) can be interpreted as 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 example demonstrating the LC paradigm, which bridges the crystal structures in real space to the band topology in momentum space.