The combination of two-dimensional crystals through the formation of van der Waals bilayers, trilayers, and heterostructures has been considered a promising route to design new materials due to the possibility of tuning their properties through the control of the number of layers, alloying pressure, strain, and other tuning mechanisms. Here, we report a density functional theory study on the interlayer phonon coupling and electronic structure of the trilayer h-BN/SnTe/h-BN, and the effects of pressure on the encapsulation of this trilayer system. Our findings demonstrated the establishment of a type I junction in the system, with a trivial bandgap of 0.55eV, which is 10% lower than the free-standing SnTe one. The almost inert h-BN capping layers allow a topological phase transition at a pressure of 13.5GPa, in which the system evolves from a trivial insulator to a topological insulator. In addition, with further increase of the pressure up to 35GPa, the non-trivial energy bandgap increases up to 0.3eV. This behavior is especially relevant to allow experimental access to topological properties of materials, since large non-trivial energy bandgaps are required.

中文翻译：

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三层范德华结构中压力引起的拓扑相变的从头算研究：以 h-BN/SnTe/h-BN 为例。

通过形成范德华双层、三层和异质结构的二维晶体的组合被认为是设计新材料的有希望的途径，因为可以通过控制层数、合金压力、应变和其他调整机制。在这里，我们报告了关于三层 h-BN/SnTe/h-BN 的层间声子耦合和电子结构的密度泛函理论研究，以及压力对该三层系统封装的影响。我们的研究结果表明在系统中建立了 I 型结，带隙为 0.55eV，比独立的 SnTe 低 10%。几乎惰性的 h-BN 覆盖层允许在 13.5GPa 的压力下发生拓扑相变，其中系统从平凡绝缘体演变为拓扑绝缘体。此外，随着压力进一步增加到 35GPa，非平凡能带隙增加到 0.3eV。这种行为与允许通过实验获得材料的拓扑特性特别相关，因为需要大的非平凡能带隙。