论文标题
单层黄金（i）的结构相变：从室温拓扑仪到辅助半导体
Structural phase transition in monolayer gold(I) telluride: From a room-temperature topologicalinsulator to an auxetic semiconductor
论文作者
论文摘要
半导体和拓扑绝缘子之间的结构相变为纳米电子中的丰富应用，但在二维（2D）材料中很少发现。在这项工作中，通过结合初始计算和进化结构搜索，我们研究了两种稳定的2D形式的黄金（i）Telluride（au $ _ {2} $ te）和方形对称性，称为s（i） - 和s（ii） - 和s（ii）-AU $ _ $ _ {2} $ te。 s（ii）-au $ _ {2} $ te是全球最小结构，是室温拓扑绝缘子。 s（i）-au $ _ {2} $ te是一个直接间隙的半导体，具有较高的载体迁移率和不寻常的平面内泊松比。 S（i）和S（ii）阶段都具有超低的Young模量，这意味着高灵活性。通过应用小的拉伸应变，可以将S（ii）-au $ _ {2} $ te转换为s（i）-au $ _ {2} $ te。因此，在au $ _ {2} $ te的2D形式中发现了从室温拓扑绝缘子到辅助半导体的结构相变，从而可以在相变的电子设备中进行潜在的应用。此外，我们借助声子光谱和组理论分析来阐明相变的机理。
Structural phase transitions between semiconductors and topological insulators have rich applications in nanoelectronics but are rarely found in two-dimensional (2D) materials. In this work, by combining ab initio computations and evolutionary structure search, we investigate two stable 2D forms of gold(I) telluride (Au$_{2}$Te) with square symmetry, noted as s(I)- and s(II)-Au$_{2}$Te. s(II)-Au$_{2}$Te is the global minimum structure and is a room-temperature topological insulator. s(I)-Au$_{2}$Te is a direct-gap semiconductor with high carrier mobilities and unusual in-plane negative Poisson's ratio. Both s(I) and s(II) phases have ultra-low Young's modulus, implying high flexibility. By applying a small tensile strain, s(II)-Au$_{2}$Te can be transformed into s(I)-Au$_{2}$Te. Hence, a structural phase transition from a room-temperature topological insulator to an auxetic semiconductor is found in the 2D forms of Au$_{2}$Te, which enables potential applications in phase-change electronic devices. Moreover, we elucidate the mechanism of the phase transition with the help of phonon spectra and group theory analysis.
