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.

中文翻译：

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拓扑晶体绝缘子LaSbTe的层结构

拓扑晶体绝缘体（TCI）是对称保护的拓扑状态之一。任何TCI都可以在其晶格中变形为几个解耦的二维（2D）拓扑非平凡层的简单乘积状态，这与称为层构造（LC）极限的晶体对称性有关。在这项工作中，基于第一性原理计算，我们发现四方LaSbTe（t -LaSbTe）和正交晶体LaSbTe（o -LaSbTe）都可以解释为每个晶格空间中二维拓扑绝缘体的堆叠。从t -LaSbTe到o的结构相变-LaSbTe由于软声子模式而演示了实际空间的变化如何导致拓扑状态的改变。基于LC分析了它们基于对称性的指标和拓扑不变量。我们认为LaSbTe是演示LC范式的理想示例，该范式将真实空间中的晶体结构桥接到动量空间中的能带拓扑结构。